Did you tried to click there, to reload the fonts?
If this does not work, close GIMP, then go to your GIMP user profile ➤ C:\Users\"yourname"\AppData\Roaming\GIMP\, inside there is a folder named "2.10" rename the folder 2.10 to "2.10-backup", and restart GIMP
This will force GIMP to re-scan all the fonts on your microsoft's windows, by doing so GIMP will re-create a new 2.10 folder (new user profile) as well, thus your preferences will not appear (it's in the now "2.10-back" folder), but you will have reset GIMP to its default setting and your fonts problem should have disappeared.
If this does not work, close GIMP, then go to your GIMP user profile ➤ C:\Users\"yourname"\AppData\Roaming\GIMP\, inside there is a folder named "2.10" rename the folder 2.10 to "2.10-backup", and restart GIMP
This will force GIMP to re-scan all the fonts on your microsoft's windows, by doing so GIMP will re-create a new 2.10 folder (new user profile) as well, thus your preferences will not appear (it's in the now "2.10-back" folder), but you will have reset GIMP to its default setting and your fonts problem should have disappeared.