The "factual accuracy" tab on film's Wikipedia page might be an ok place to start...

The general consensus of leftists who are into ecology is that movie is right that just green tech under capitalism won't be enough to stop global warming, but it uses outdated stats, unnesesarily shits on a bunch of activists and instead of coming to the right conclusion, that we need socialism, degrowth AND green tech, it just goes black pill and ends up giving ammunition to reactionaries in the end.