I keep seeing posts from this instance referring to capitalists as liberals. Since when are capitalism and liberalism related? As far as I’ve always known, liberalism is a social ideology, while capitalism is an economic system.

Liberalism and capitalism were always related because liberalism is one of the ideologies of capitalism (the other being fascism), You don't have to be a capitalist to be a liberal.

Liberalism is an economical ideology before all. All the rest is aesthetics and rhetoric that liberals adopt and discard willy-nilly depending on what is politically convenient at the time.

Why do y’all refer to all capitalists as liberals when at least half (probably more, at least in my experience) are conservatives?

Because conservatives are liberals. The dichotomy commonly accepted by both sides in the US that conservatives and liberal are of different ideologies is a false one, with the exception of the minority ones who are out right fascists, conservatives and right libertarians are liberals, they just have a socially anti-progressive stance because their voter base is socially anti-progressive, refer to my point from above:

Liberalism is an economical ideology before all. All the rest is aesthetics and rhetoric that liberals adopt and discard willy-nilly depending on what is politically convenient at the time.

I, for example, consider myself a liberal, but I’m most certainly not a capitalist. I’m stuck in a capitalist society in which I have to play by the rules if I want to feed my family, but that’s as far as my support for the system goes. I’m pretty sure a lot of Americans feel this way.

So are the vast majority of conservatives. That doesn't make them any less pro-capitalism.

Looking it up, the definition of liberalism specifies a belief in maximum personal freedom, especially as guaranteed by a government. Considering that 90% of governments in the world are endlessly corrupt, capitalist or not, I’d much prefer one that guarantees its citizens rights as a matter of course rather than begrudgingly grants them privileges that can be taken away without public oversight.

This definition is almost good but the implications of omitting the things it omit make it effectively a lie.

What freedoms are we talking about exactly? Not every freedom is desirable or even possible, the right to fly by flapping your arms is technically a freedom but no matter how hard I sign fancy papers saying that any human in my backyard has that right, that won't magically grant peoples in my backyard the ability to fly by flapping their arms, the right to murder and dismember humans is also technically a freedom and it is possible to grant it, but I don't need to explain why we shouldn't.

"Freedom" as liberal conceive it is, to put it bluntly, gaslighting. It almost never go beyond "technically, the fancy legal document signed by some politician say you can do this thing" but can you really though?

Here is an example: in the US you, as a worker, on paper have the right to quit your job whenever you want, but can you really though, if you are to poor or too indebted, then no, you can't, you have to stay until you find a new job willing to take you and that is no worst than the current one if possible, and only then, at the cost of many hours of job scouting on top of your working hours, can you maybe afford to quit. And that's just one example of many instances of that kind of things, not only in the US but in all existing liberal "democracies".

The only freedom liberal states consistently grant, let alone enforce, is the right (for the capitalists) to own private property and extract surplus from other people's work.

Many of the supposedly unconditional freedoms you can't actually enjoy if you are not wealthy enough.

Similarly, your take on governments, while somewhat grounded on reality and your personal experience, is ignoring such important things to consider that it makes it plain wrong.

In particular, the government's class character.

States are not some kind of magical monoliths completely cut of from the societies they rules. They are tools of class warfare and a necessary product of class struggle, they are the way the ruling class of a class society guaranty their privileges and supress oppositions to the ruling class by the exploited class. This is the true reason why your supposed "democracy" won't pass free healthcare, crackdown on big corporations or make lobbying and corruption illegal etc despite these and many others being widely popular even among conservatives despite what the most vocals of them says: under capitalism, the bourgeoisie is the ruling class, they are the one who hold the economic power and therefore the political power (the 2 are irremediably linked in various ways) and as such, they always have the last word (this is what we call a dictatorship of the bourgeoisie), and they will continue to have it for as long as they are not expropriated and overthrown.

Once the bourgeoisie is overthrown, have enough of their private property seized to guaranty that they won't be able to use economic coercion against the revolution, and once a proletarian state in which the bourgeois are not allowed to participate (a dictatorship of the proletariat) is created, all of the problems you listed could, at last, be progressively done away with.

Emphasis on the progressively, that will be a possess that will obviously not be instant nor linear and will demand lots time and resources to do.

For more details, read Marx, Engel, Lenin, etc... Feel free to ask for recommendations.

Do y’all really trust your governments to look after your best interests? As a U.S. American, I know I wouldn’t trust my government or politicians to do anything but enrich themselves at my expense, but I don’t have to; my rights are guaranteed by our constitution.

Now if we could just get them to stop funding and committing genocide…

See section just above.

Those things happen because the current American state is a dictatorship of the bourgeoisie. The goal of the bourgeoisie is to keep enriching themselves more and more every day, and as such, the state under their control act accordingly.