Some fonts are rendered as boxes

I was unable to locate the mentioned folder.

Oh, I see from you previous post that you’re on Windows 11. The above recommendation is for Mac, so yeah, the path would be different.
You app data for Windows is located by default at C:\Users[YourUserName]\AppData\Roaming\FontBase
Try making a reserve copy (to save your current app data) of this folder and then deleting it.
If should have the same effect as the one mentioned in the workaround linked above.
Hope this helps,

It didn’t work for me. It’s happening with Artegra Slab for me.

Maybe this is some weird, old nonstandard encoding?