But the rules of the forum are too restrictive to allow me to speak freely, and I don't like being restricted, so I may not come back to the forum to speak in the future.
Nothing is preventing you and others from having free speech in this forum, so you have unwittingly drawn the wrong conclusion about it. You just need to evaluate what you have done so that the moderators delete your post, this is a different matter than what you call free speech.
Having thick skin is the best advice for the current situation but if your interest in being in the forum has dropped then take a break and come back when you have better interests and feelings. But believe me, deleting posts that violate the rules based on the moderator's interpretation is not a valid reason to say you are prohibited from speaking. You must obey the rules, so you should know more about the rules so that in the future not many of your posts are deleted.