I posted a topic on Fifefox being locked as default browser, please read that first, sry.
As it turns out, I also have an issue with Thunderbird,
I decided to remove FF, and have only Vivaldi, so it lauches it by not having other choice, it does launch Vivaldi, but this happens.
Every single time I click a link inside TB, launches Vivaldi, and throws it out of sync.
I tried both the repo TB, and the flatpak TB, same result.
Is anyone else with this issue?