SUMMARY
In a Wayland session, the side buttons of a graphics tablet stylus are swapped in Chromium. I use the default arrangement: Lower button for Right-click, Upper button for Middle-click. Things work as intended in pretty much everything except Chromium -- it becomes Lower button for Middle-click, Upper button for Right-click for some reason.

I'm reporting this based on a Huion Kamvas 16 Gen 3 with Opentabletdriver. I will attach more information with Wacom devices with linuxwacom in later comments.

STEPS TO REPRODUCE
1. Login to a Wayland session
2. Click on desktop using the stylus buttons
3. Click in Chromium using the stylus buttons

OBSERVED RESULT
The functions of the side buttons are swapped only in Chromium.

EXPECTED RESULT
The functions of the side buttons are the same as in other places.

SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux 
KDE Plasma Version: 6.3.6
KDE Frameworks Version: 6.18.0
Qt Version: 6.9.2
Kernel Version: 6.17.1-0-MANJARO (64-bit)
Graphics Platform: Wayland