Hacked apple ID

Someone hacked into my old apple account 10 days ago. I managed to get the account back with apple support. We checked my account together, theres no devices linked to it other than mine, password is changed 2FA is activated. Then I changed my email password and checked if there is any unrecognised activity on my email account, theres none. Seems all good. Then this morning, i received an email that they disabled my 2FA, changed my password and enabled a new 2FA. I disabled it, changed my passwords again and enabled my own 2FA. I got my apple account back. I checked my email again, and its still seems to be secure. Also changed the password to everything.

Theres no payment details on it or anything because it wasn’t used. But I have a few questions if anyone can help me.

How does this happen?
How did they disabled my 2FA?
How can I secure my account to prevent this person from getting into it again?
Why do they keep on getting into my account even though there’s nothing like payment details on it?
And what should i do now?

I read someone else’s experience on reddit with deleting the account, someone else reactivated it and now they cant access it anymore. So im worried about just deleting the account.

I would really appreciate any advice I can get. Thank you!