Hello,
Thank you for posting in Microsoft Community forum.
Based on the description, I understand your question is related to Windows 11 invisible letters in 'All Apps' Alphabet block.
Try go to Settings > Personalization > Themes, select the default Windows theme and font settings, remove other custom themes.
Go to Device Manager and check your graphics drivers, update them in Device Manager or via manufacturer's website.
Go to settings > Update & Security > Windows Update, check for any pending updates. Check if the latest windows update has been installed.
Have a nice day.
Best Regards,
Molly