I have had luck with applying i8042.reset to my bootloader to fix the keyboard not working on cold boot.
I am running Pop!_OS 20.04 LTS, so to apply the option I had to append `i8042.reset` to the options line in my /boot/efi/loader/entries/Pop_OS-current.conf
I hope this helps others.
I am also having the same issue with the same laptop (UM425UA Ryzen 5 5500U + 16GB RAM version)
Is there any debug information I can provide to help solve the issue?