Chrome on MacOS sends only a single keydown event when turning on caps-lock, and only a single keyup event when turning off caps-lock. In contract to firefox on MacOS, that sends always only a single keydown that is properly handled in quirks as capsLockKeyupUnreliable.

Steps to reproduce:

In my tests I always clicked CapsLock twice, while initial state was not activated. So I activated and deactivated caps lock in Firefox and Chrome on MacOS while watching how guacamole keybaord behaves and also what events are actually fired:

Firefox MacOS:

Chrome MacOS: