Yea, it looks like they sent their original email to several people, but failed to send it to the list. And they didn’t include any of the specifics in the email (such as kernel versions), instead giving a link back to their blog post. Whether you use email to report a bug or a bug tracker, you _must_ include all relevant information in the report itself. Even if it means repeating yourself, or coping and pasting from your blog.
Edit: Actually, they might have remembered to CC the mailing list, but since they use Proton Mail it probably sent the email encrypted. Don't send encrypted email to mailing lists.
The lists reject HTML emails entirely, and most mail clients don't make the choice between sending plain-text and HTML emails obvious (if they offer it at all)
Ideally, mailing lists would make some effort to keep the plain text content in HTML emails rather than just throw it away. If lynx can render full pages in a console, surely we can degrade HTML down to plain-text without too much effort.
Rejecting people who have not taken the time to setup their email client is tradition, but not very helpful.
Edit: Actually, they might have remembered to CC the mailing list, but since they use Proton Mail it probably sent the email encrypted. Don't send encrypted email to mailing lists.