Their algorithm is not interfering with your free speech because you have no right to free speech on THEIR platform. Facebook can manipulate you, shame you, ban you, etc. from their platform and you have (practically) no recourse. They don't owe you anything, you chose to use their service and abide by their rules. No one is forcing you to use them or any platform (whether or not you feel social pressure to do so is another matter). I choose not to engage with most social media and am much happier for it.
All that said, I DO think some social media platforms have overstepped their Section 230 protections and are dipping their toes into publisher territory. They want their cake and to eat it too.