Please tell us some basic information before asking for help:
Model Name: Zenfone 9
Firmware Version: no idea
Rooted or not: no
Frequency of Occurrence: often
I'm using the classic navigation with three buttons.
The right button (recent apps) does not work as expected.
1. When I press it repeatedly, I would expect it to always alternate between the last two apps. But often it doesn't. Sometimes it switches to the home screen, sometimes it switches to the third app in the list.
2. When I click the button just once, I would expect it to show me the "minimized" version of the app I'm currently in. But often it goes to the second and sometimes third app.
There seems to be a timing issue (and maybe more issues here). The faster I tap (and I do that naturally because double tap should normally allow me to switch between my last two apps quickly), the more often strange behavior occurs.
For good reference behavior, check the Google Pixel. My previous phones were Pixel 1 and Pixel 3, both of which worked correctly all of the time.