Proton games do not launch in KDE Plasma Wayland session

**Game information**
All games run using Proton. Specifically observed with YS VIII: Lacrimosa of Dana, Nier Replicant v1.22, and Sonic Mania.

**Distribution name and version where applicable**
```
~$ cat /etc/os-release
NAME="openSUSE Tumbleweed"
# VERSION="20220324"
ID="opensuse-tumbleweed"
ID_LIKE="opensuse suse"
VERSION_ID="20220324"
PRETTY_NAME="openSUSE Tumbleweed"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:tumbleweed:20220324"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Tumbleweed"
LOGO="distributor-logo-Tumbleweed"
```

Desktop environment:
KDE Plasma 5.24.3
Wayland session

**Flatpak info**
```
~$ flatpak --version
Flatpak 1.12.7
```
```
flatpak --gl-drivers
default
host
```

**Problem description**
Steam games running via Proton do not launch at all when Flatpak steam is running in Wayland session. The play button state changes to STOP and then the game process seems to die before drawing any UI.

[Error log](https://gist.github.com/ishchow/c838325227d0fce76c4b42c90e20378f)

Seems there is an earlier issue filed with GNOME Wayland two years ago: #578. But error messages from that issue seem to be different and that issue was fixed by sdk update. Running `flatpak update` did not fix this issue for me.

**Does this issue reproduce with native Steam**
Does not reproduce with native steam (either with X11 or Wayland). Does not reproduce with proton games in Flatpak Steam + X11. Does not reproduce with native games in Flatpak Steam + Wayland (ex. Celeste).