Fediverse

Yes that is the reason.

Not because of the many other reasons like we don't have an algorithm set to be as addicting as possible, dark patterns, rage bait, millions of dollars in marketing and astro-turfing, so many other things that go into your average popular social media network.. I mean there is a reason facebook has so many employees.

No no it's because right wingers get their fee fees hurt when people don't abide their rhetoric.

Mods or instance owners? This place was never designed to be a free speech zone.

this site

This isn't a site. It's a collection of sites (instances).
If there is an instance that doesn't tolerate your kind of speech, then choose another instance that does.

Be aware that two of the largest hardcore left-leaning instances (hexbear, ml) have been widely defederated (instance-blocked), so it's not fair to say that this only happens to right leaning or centrist ideas.

The beauty (and point) of Lemmy and fediverse is that if you feel like you're being censored, you can join or make an instance of like-minded people, while still having access to the other area if you want it.
Lemmy is uncensorable, but doesn't force people to listen to you.