Steps to reproduce:

1. Install clean Ibexa DXP v4.1.
2. Use it for a bit.
3. Observe var/log/dev.log.

Result:
There are plenty of deprecation messages (they can be disabled but still, something worth taking care of). Not all of them are coming from Ibexa's bundles but we could get rid of at least some of them.

Note:
Obviously, deprecation notices can be disabled by a developer in the monolog configuration.