https://bugs.freedesktop.org/show_bug.cgi?id=108979
--- Comment #2 from emmeci@linuxmail.org ---
From 1:00 you can see the popup missing texture, using the Padoka Unstable
https://youtu.be/dCxsWEr2pOw?t=61
Note that this problem is more frequent on Mesa shipped with Padoka Stable and Oibaf PPAs, and nothing on the 18.0.5 shipped as default from Canonical.
I wasn't able to reproduce this issue on Firewatch with Padoka Unstable in a 5 minute gameplay, but i have experienced the same with the Stable on that game, and nothing with the Canonical version.