(original bug reporter replying, thanks Matej for pointing me here!)

> what OS and font gives this error?

OS is openSUSE Tumbleweed 20211202, which has these versions:
- python 3.8.12
- tcl/tk 8.6.12
- fontconfig 2.13.1
- adobe-sourcecodepro-fonts 2.030

Previously installed (working) version was 20210114, which had:
- python 3.8.6
- tcl/tk 8.6.10
- fontconfig 2.13.1
- adobe-sourcecodepro-fonts 2.030

I am not sure if tk uses fontconfig or what other libraries tk uses to load fonts. I can give versions for all packages.

> Please run the following, also uploaded, with the offending font, replacing the name I used.

Result: 7 lines with "0" (zero)

(regardless of which font name I use, either installed, such as 'Cousine', 'Source Code Pro', or not installed, such as 'XYZ')

> print(tk.call('info', 'patchlevel'))

Result: "8.6.12"

> add the line 'r.mainloop()' at the end of the script

Result: A tiny window without text

I also tested Python version 3.9.9 on the updated system, which had the same issue.