Syntax Highlighting Settings are lost after "some days"?

The Thunderbird (128.8.1) of my work computer is usually running for days/weeks without reboot nor restart.

Every couple of days (for example, I left it Friday evening, and got it back this Monday morning, so let's say ~36 hours running without me actually using it), MHR's behavior is weird: syntax highlighting is displaying <span class="hljs-comment"> (or hljs-keyword, hljs-title, etc.): Screenshot_20250324_104113

I then have to restart TB. But yet, it's not enough: although the Theme is still set to Github Dark, it's not actually applied: Screenshot_20250324_104203

I have to select another Theme and reselect the one wanted to, at last, get it working back: Screenshot_20250324_104220

(A few weeks/months ago I found another issue describing the same kind of behavior, but I cannot find it anymore)

  • Markdown Here Revival: 4.0.3.3
  • Thunderbird Version: Thunderbird 128.8.1 20250317192722
  • Operating system: linux x86-64