Hi Guillaume, welcome to the Community!
Invoices can be found at https://my.atlassian.com/product. Note that if you're on the free plan you won't have any invoices, as you're getting the service for free.
Let us know if you have any questions,
I finally figured out that you have to be the primary technical contact to have access to invoices.
"As a primary technical contact, you can access current and future orders and invoices, and manage your linked Atlassian products."
Besides that, this is not logical, it's interesting that even support does not know about it.
Beginning on April 4th, we will be implementing push limits. This means that your push cannot be completed if it is over 3.5 GB. If you do attempt to complete a push that is over 3.5 GB, it will fail...