Canonical announced some time ago their Steam Snap which was promoted as stable with Ubuntu 23.04, as they continue to push their own packaging format with Snap but it seems this has been causing problems for Valve.
Writing on Mastodon, developer Timothee "TTimo" Besset, who works on various things for Valve posted asking people to consider using the official Valve .deb package or at least consider using the Flatpak:
Valve is seeing an increasing number of bug reports for issues caused by Canonical's repackaging of the Steam client through snap.
The best way to install Steam on Debian and derivative operating systems is to follow the instructions at http://repo.steampowered.com/steam/ and use the official .deb
We are not involved with the snap repackaging. It has a lot of issues.
If you don't want the .deb, please at least consider the flatpak version.Timothee "TTimo" Besset
So if you've been having various problems with Steam on Ubuntu (or a derivative like Kubuntu), it may be because you've installed it as a Snap. Worth trying out the official .deb or Flatpak to see if it runs better for you. You can also give Canonical feedback in your issues on their Discourse Forum and report issues to Valve on GitHub (if you're using their official packages).
Hopefully Canonical can look into any issues.