"ZZ_DO_NOT_USE Placeholder" Game showed up in library

[Awk34]

Your system information

https://gist.github.com/Awk34/35e4b51cb33d59345424428bd037c44e

• Steam client version (build number or date): Jan 16 2022 17:34:49
• Distribution (e.g. Ubuntu): Mint
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

I didn't see this in Windows. I rebooted into Mint and saw a "ZZ_DO_NOT_USE Placeholder" item in my library:

Steps for reproducing this issue:

1. Open Steam Library

[kisak-valve]

Apparently related to Age of Empires IV Ranked Seasons, appid 1892320.