i genuinely think the problem is threefold:
- the physical switches (the interaction between the rubber and the clicky switches, which themselves are not great since the click feedback is not 100% of the time in sync with there being an actual closed electrical connection)
- the keyboard firmware (i have not used the official firmware beyond like day 2, in my experience Jack Carter Smith’s works a lot better with optimisations)
- whatever software you use not handling the keyboard FIFO robustly enough to avoid dropped keys, or worse, buffering keys in a way that you get old key presses instead (this happened on my own firmwares until i implemented some fixes)
with proper keyboard firmware, and pico software that handles the I2C better, i have noticed a significant decrease in typing issues. that does not mean it fixes the physical issues with the keyboard switches which also cause drops
that said, i can’t speak to your issues upgrading the firmware, sorry