Don't use Facebook (including Instagram and WhatsApp), Twitter, TikTok, Tumblr, really any social media app or messenger, forum, or even Discord if you are seeking an abortion. Only use things like Signal (assuming it's still safe) that are heavily point-to-point encrypted.
Tech corporations aren't your friends, they will rat you out to fascists.
As several people pointed out in the notes already, but don’t trust Signal either. Only communicate through messengers or emailers that allow you to encrypt your messages. If you live near folk that will help you, please only speak to them about it instead and on over any apps.