Hi @Seeasoftware Eric PAPILLIER , welcome to Microsoft QnA forum.
Currently scaling up from Basic tier to other tiers is not supported in Azure Database for MySQL. If we go to pricing tier in Azure portal, we would find the options locked as shown in below screenshots.
However, we can still achieve it using the backup and restore process but again it would be a new database. Please check the below articles for the same:
How to Scale up Azure Database for MySQL from Basic Tier to General Purpose Tier
Upgrade from Basic to General Purpose or Memory Optimized tiers in Azure Database for MySQL
Please let us know if this helps.
----------
If answer helps, please mark it as 'Accept Answer'