Looks like a low level issue.
Worth trying to run it with OpenJDK 11. Link here: https://www.b4x.com/b4a.html
Note that in most cases you don't need to run B4A Sdk Manager.
I remember having the same problem with Android Studio. The fonts were corrupted in the same way.
I finally tracked it down to my upgrade from Windows 8 to Windows 10. For some strange reason Windows decided to delete some of the fonts. Fortunately, I was able to get the old fonts back from a backup.
Once I had done this all was fine.
Have you done an upgrade recently or made any changes to your system fonts?
Try going to Windows->Settings->Font Settings and scroll through all the Font examples to see if you can find the dud one.
If you find it, you can uninstall it, see if the problem changes and/or re-install that Font.