If you want to, you can set your Mastodon account into follow request mode, so that any follows you get from other people have to be manually approved by you. Here's how to do it:
➡️ https://fedi.tips/restricting-who-can-follow-you-in-mastodon
When you do this, a little padlock 🔒 will appear on your profile.
When you receive a follow request, your server website or app will let you know and you can click ✔️ or ❌ depending on whether you approve or deny the request.