OS Graphics problems when I start Steam on Ubuntu 20.04

[Redeadly]

Your system information

• Steam client version (build number or date): Last, downloaded from steam site, ubuntu software or through console and always uninstalled by console
• Distribution (e.g. Ubuntu): Ubuntu 20.04.4 (always updated)
• Opted into Steam client beta?: [Yes/No] No
• Have you checked for system updates?: [Yes/No] Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. Please link any large code pastes as a Github Gist

Hi,
When I start Steam all OS gfx change and become unreadable.
I have attached a screenshot.
My specs:
AMD® Ryzen 5 3600 6-core processor × 12
AMD® Radeon rx 5700 xt
16Gb ram
Ubuntu 20.04.4 LTS
64-bit
GNOME 3.36.8
X11

Best regards,
Davide

Steps for reproducing this issue:

1. Start steam
2. The login window appear
3. Wait from 0 to about 5 seconds and the graphics get messed up