Hi @Sébastien FALQUIER​ it works for me, there are no restrictions. Maybe the PAT token you generated for the service principle got expired. Can you generate a new token and try to run GET/git-credentials API?

How are you creating PAT for service principle? If you use api/2.0/token-management/on-behalf-of/tokens make sure to set lifetime_seconds to a longer duration.

Mark this comment as "best answer" if this resolves your query.