I feel like now I know why this happens. Look at these buttons from the new reviewer —
I mean look at the colours we have. I already think it’s easy to categorise the buttons into Good+Easy/Again+Hard. If you now look at the colours Again+Hard have very similar looking colours.
I’d expect the colours to communicate something but here they have the potential to miscommunicate. Making Hard+Good+Easy different shades of the same colour (or different but similar colours) might be a good idea (I mean, all green can confuse you). But clearly, something needs changing here.
(I checked and found the same issue with AnkiMobile)