Rated 5 out of 5 stars

>I have second confirmation that b1 solves the linux pdf issues, did you try it?

I'm not sure what you mean with "b1". If Thunderbird 91.9.1: Yes, I tried. Does not work.
I'm sooo sad about that.

This review is for a previous version of the add-on (12.0.0).  This user has other reviews of this add-on.

Sorry I was not explicit, b1 is first beta for v12.0.1 with the pdf fix. You can download it here :
https://github.com/thundernest/import-export-tools-ng/blob/v12.0.1/xpi/import-export-tools-ng-12.0.1-b1-tb.xpi
Christopher