Hi Cyril AUQUIER I want to help you with this question.
I have answered a similar question in another thread recently.
Please check out the thread: https://learn.microsoft.com/en-us/answers/questions/1655729/im-getting-502-badgateway-and-cannot-create-or-upd
I hope this helps you to solve the problem.
If none of my approaches helps you, try to deploy the resources in another region.
And lastly, I recommend opening an official support ticket.
If the reply was helpful, please don’t forget to upvote or accept it as an answer, thank you!