OK, I have changed your topic tag form app:desktop to app:browser.
What are you trying to auto-fill? Login credentials or credit card information?
And why do you say that you have to disable Bitwarden’s browser extension? What happens if you don’t?
I have tested using the Buy with Gpay button on the demo site below, and auto-filling of username and password works without issue — can you check if you are able to reproduce your problem on this demo site?