There's a ton to say here, but I think the right thread to emphasize is that the environmental movement in general has some seriously racist and classist historical roots. In particular, a lot of the early environmental movements were deeply wrapped up with the popularity of eugenics in the 19th and early 20th centuries, both of which were tremendously influenced by Thomas Malthus' 1798 work "An Essay on the Principle of Population," which argued that the main cause of human suffering and poverty (both historically and at the time he was writing) was an increase in population--especially non-productive members of the population--beyond the carrying capacity of the environment. This, Malthus argued, would inevitably result in famine, mass deaths, and tons of human misery in general.

This "Malthusian trap" idea was very popular with 19th and early 20th century progressives, and was often interpreted to mean that the poor, people in underdeveloped areas, and really anyone that was seen as "non-productive" in the standard capitalist sense ought to be (at the very least) sterilized for their own good. Margaret Sanger, a very prominent early women's rights advocate and birth control pioneer in the 1920s, was very much motivated by this kind of concern:

“If the millions of dollars which are now expended in the care and maintenance of those who in all kindness should never have been brought into this world were converted to a system of bonuses to unfit parents, paying them to refrain from further parenthood, and continuing to pay them while they controlled their procreative faculties, this would not only be a profitable investment, but the salvation of American civilization [...] I believe that now, immediately there should be national sterilization for certain dysgenic types of our population who are being encouraged to breed and would die out were the government not feeding them.”

Contemporary ecofascism is usually traced to Mussolini and Hitler's shared idea of "living space" and "returning to the land" in their various regimes, especially Mussolini's 1921 article "Fascism and The Land." Quoting from this piece from Columbia University:

By 1930, Mussolini’s “land improvement” campaign announced that they were “witnessing a return to 'Mother Earth'” with more productive agricultural land for the empire. Mussolini reclaimed the land of the former Roman Empire by invading countries in Europe and Africa, executing political adversaries and murdering hundreds of thousands of people. In Germany, Hitler was influenced by Mussolini’s fascism to justify an innate connection between a superior Aryan race and the purest of land. As a result, 400,000 people with disabilities and minorities were sterilized before World War II, and as many as 17 million people were killed in the name of eugenics by the end of the war.

After World War II, open endorsement of eugenics got a lot less popular in liberal democratic circles (I wonder why!), but the "Malthusian trap" myth persisted for much longer, and continued to motivate a lot of foreign policy in the NATO world. In 1958, Eisenhower told his national security council that the best way the United States could help underdeveloped countries was to check their population growth, and promoted the idea that the distribution of contraceptives was the most effective way to fight poverty (and thus communism). This resulted in all sorts of terrible shit happening, including the marketing and shipment of birth control devices that were extraordinarily dangerous to women and banned in the United States being shipped off to developing nations to help fight the Malthusian scourge. Garret Hardin , the economist responsible for the "tragedy of the commons" idea, openly advocated against sending food aid to developing nations for what look like pretty explicitly fashy reasons. Quoting from the previously linked piece:

Concerned that ethnic solidarity would lead minorities in the United States to liberalize immigration policy, Hardin argued that “[t]he double question Who benefits? Who pays? suggests that a restriction of the usual democratic franchise would be appropriate and just in this case.” Moreover, he regularly insisted that to prevent catastrophe, American culture would have to adopt radically new values, especially regarding reproductive freedoms. In 1963, Hardin began publicly advocating for women’s reproductive rights. With the 1968 publication of “The Tragedy of the Commons,” however, he began calling for the United States to reject the UN Declaration of Human Rights, explicitly arguing that the government should adopt coercive measures to prevent women (especially, as he argued elsewhere, non-white women) from reproducing. According to Hardin, certain racial groups have “adopt[ed] overbreeding as a policy to secure [their] own aggrandizement,” and because of this, he argued, “the freedom to breed is intolerable.”

The emergence of COVID in 2020 revitalized a lot of these tendencies in public discourse, which is why I think it's especially important to talk about this right now. Early on in the pandemic, what we might call "clean nature porn" emerged as a genre on social media, with pictures of clear skies, clean canals, and other environments returned to their "natural" state--ostensibly as a result of COVID-cased decrease in greenhouse gas emissions. While it's true that COVID did cause a modest decline (I think it's about 5%) of GHG emissions over 2020, this framing of the issue was the thin end of a wedge for ecofascists. The idea that "humanity is the virus" and that nature could recover if only enough people (and, presumably, the right people) died of COVID started to get repeated and amplified by various crypto-fascist personalities on the internet. This is really just a repackaging of the same old Malthusian idea that our most significant problem--the driver of poverty, starvation, misery, and environmental destruction--is a dearth of resources and a human population beyond the carrying capacity of the Earth. This is, to put it bluntly, totally fucking wrong. We have more than enough food to sustain the global population, and we have the technology that would be necessary to convert our global economic system into a carbon negative one. Our problem is not a lack of resources, but rather a lack of a system that equitably and fairly distributes those resources but instead prioritizes short-term economic gains over long-term sustainability and environmental responsibility.

It's this "humanity is the virus" narrative that I think is most concerning and most worth combatting (at least right now). Even well-meaning liberals can be taken in by this sort of argument, and it's no more sensible now than it was when Malthus was writing in 1798.

There's a ton more that could be said about any aspect of this, and I'm happy to go into more detail about particular points if people are interested, but that's the (not so) short version of the points that I think are important to make.