Thank you for your suggestion of retention policy.
The problem is that I am using Duplicati with a cold storage. Therefore I have disabled the auto-compact option (as mentionned here Azure Blob - Using Archive Access Tier - #6 by kenkendk. By the way does the auto-compact really need to download the files? Can’t it use the local database instead? In that case maybe I can reactivate this option.)
And with the auto-compact option disabled I thought it was preferable not to do back-ups so often to limit the size of the back-up. What do you think?
I agree. When you do so with Duplicati you get an error message. It shouldn’t be the case. It scares the user whereas everything works well.