On my phone it looks perfect (well, yellow, green and then just blank spaces for the wrong/black squares). I'm on iOS 15.2.1 with my phone.
However, in Safari on my MacBook, it's weird little squares and blank spaces.
But I'm also still on Mojave (10.14.6) from 29 years ago, so I almost don't expect things to look right/as expected here sometimes.
My iPhone (iOS 15.2.1):
My MacBook (Mojave, 10.14.6):
PS - I play only on my iPhone (because it's usually the middle of the night, etc.). So I just keep the streak/stats going from that one device. I never play on my Mac.