Pixel 7pro call answering

[Ja593]

My pixel 7pro seems to have two different incoming call notifications. 

The normal swipe up circle works fine but on occasions I get a square block near the top of the screen.  Tapping the green answer button does not answer the call and I am left with having to call the sender back.

[Ja593]

Took me three tries today to answer an important  call today. Pressed the square button firmly on first two to no avail.  Fortunately they rang back as it was private number. Someway when I pressed the homebutton quickly the swipe up button appeared. Will try this again if I get the opportunity. 

[Ja593]

Would seem to have answered my own question by pressing the green answer square then short press on the side/power button, screen then displays the round swipe up phone button. Vodafone forum suggests similar but using volume up or down button press.