Your system information

• Steam client version (build number or date): May 19 2021 at 01:54:04
• Distribution (e.g. Ubuntu): Ubuntu 20.10
• Opted into Steam client beta?: Tried with and withoutYes[Yes/No]

Please describe your issue in as much detail as possible:

• I launched Civilisation 6 from the app shortcut.
• Gameplay seemed a bit sluggish but I figured my laptop was slow.
• Eventually exited the game; noticed that steam was still using 100% of a core even though the game finished.
• I was running the beta client; I reverted to the non-beta client; stopped steam and tried again, same result.

Steps for reproducing this issue:

1. Launch Civ 6
2. Exit Civ 6
3. Observe 100% CPU usage from steam

I grabbed the htop tree view as described in another issue. HTMLController and steam steam://rungameid/289070 seem to be using the CPU.