Recently, we discovered that High Contrast Mode has this issue on some of the backgrounds. The good news is that the fix should be in the next release. Make sure to update to the latest version.
In the meantime, there is a workaround for this issue.
1. Please go to the in-game settings (the gear icon ⚙️ on the bottom right of the home screen) > Accessibility > Make sure High Contrast is set to OFF, and recheck the puzzle.
(If it's off, but the issue still exist, toggle it on and back off)
2. Check the puzzle to verify if the High Contrast Mode is turned off. The letter wheel and the puzzle boxes should be slightly transparent when it's off.
ℹ️ If the High Contrast Mode is turned off and you still see the issue, try switching it on and off again to see if it solves it.
We apologize for this inconvenience. We hope this information was helpful! 😊
If not, please let us know, and a support agent will be with you shortly to address your issue.