I'm glad that you were able to resolve your issue and thank you for sharing the info.
Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others", I'll repost your solution in case you'd like to "Accept" the answer.
Issue:
Azure Front Door gives a 403 Response
Analysis:
You confirmed that you were able to fix the issue and it was unrelated to the AFD
Cheers,
Kapil.
Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.