Another update: i have received a reply on the EU ODR from OpenAI. The issue has been resolved. I will mark this reply as the answer.
For anyone who has had their account unjustly terminated, this is what you can do:
If you are an EU citizen, you get your OpenAI services from OpenAI Ireland Ltd. Then you can open a dispute using the ODR platform. For this you need to enter an email address, I used this one: dispute-resolution@openai.com
Alternatively, you can send an email to the above mentioned email. Or, probably better, you could fill out the form linked in the terms of service of OpenAI.
At a last resort, you can send a letter to their address.