If ur a popular user with tons of followers and not trans, but with a very wide range of transphobic followers (when you yourself are a trans ally) it means they find you safe to follow.
Please do better to make sure they know you support us and that you despise people like them. You're not at fault if you don't check every single follower you have but you're at fault if your attitude is considered safe for a lot of transphobes to flock to when ur cis.