No?
> In Poland, for example, Youtube, in wholesale, blocks channels which are criticize on LGBTQUERTY.
YouTube is US based and hate speech is looked down upon in the US. Don't like it? Find a service not based in the US.
> The question is why the are able to censor content.
It's a private website, they can do whatever they want. Again, find another site if you want hate content.
> I don't expect that my supplier turn off gas for me, if he thinks, that I use it to kill people; it's not his business, ot's the matter of law enforcement, the police, etc.
???
A) if they know you're using it to kill people they would be an accomplice in the eyes of the law
B) they would have every right to refuse service
Vendors always discriminate on what they ship to customers. It is never an open platform. I know it's very confusing, but Youtube literally says that you can only distribute certain kinds of things using their service and that they will block other things. I suppose they don't put it in 40 point font on their front page, but it's also not hard to find: https://www.youtube.com/t/terms (incidentally this came up in Japanese for me, so I suppose it might come up in Polish for you).
When people talk about freedom of speech and censorship, what they are talking about is society's role in gagging you. Generally speaking, usually countries don't force you to carry specific content (ha ha! Unless you are Canadian.... Canadian inside joke...), but likewise nobody is forced to carry all content, or accept all trade that might come their way. You are allowed as a business to choose what you want to do and who you want to do business with -- unless it's with a protected segment of society. That's a pretty basic freedom and someone who clearly values freedom as you do can surely see why it is important.
You might argue (to greater or lesser success) that Youtube is a pubic carrier and should be forced to carry everything for free... I suppose... But I'm betting you'll be in the "lesser success" category there. You might argue that your particular subgroup of people who criticise minority gender issues are worthy of special protection and therefore should have a protected ability to spread your message... I suppose... But seriously, I don't think you'll get very far with any of it.
From my perspective, I just think Youtube is within their rights to do what they want on this kind of issue. We may like it or dislike it, but it's the only sane way to handle it.
https://gizmodo.com/youtube-no-we-wont-remove-these-videos-o...
(And no, they're not blocked in Poland.)