I have that same problem , just posted a duplicate in Keyboard duplicate keys 
I have a little python script listening on /dev/input/event2 (AT Translated Set 2 keyboard) I used to trace this down and it gives me mostly around 30ms repeat rates which are not really achievable manually. I am also running arch/Manjaro but I doubt it is software ..
Btw no solution yet after close to two years? And I thought I was tolerant. I have been seeing this since April 2026 when I got the laptop..