@claudiamiles
It would be the owner of mindly, who owns the instance/server you are on, who removed your post. Not mastodon.
Somewhere there is a list of mindly's rules of conduct, to which one agrees to observe when signing on to the server. Perhaps you can find an answer there.
Also there is likely contact info where you can inquire why your post was removed.
mastodon.world allows political posts if you'd like to sign up here.
Welcome. Happy you are on your way.
I originally got on an environmental oriented mastodon group. Then switched to world.