the solution suggested by @carmenfdezb and @attah worked only for some time on my device: in less than a day open.desktop.url got deleted by itself. Tried many times, rebooting or not doesn’t affect this.
With my non-existent knowlwdge I feel this is not a problem with individual apps. It is about the browser disappearing from the list, due to some process erasing open.desktop.url from the system.
If Sailfish is left with only one option to open links it will use that one, in the OP case, Fernschreiber. @lumen it yould be interesting to know if you have other files other than
harbour-fernschreiber-open-url.desktop
in
/home/nemo/.local/share/applications
As @thigg says, this shouldn’t be about Fernschreiber…
If confirmed, may the title be tweaked?
I hope Jolla files (and fixes) the bug for what it is and does not overlook it as a Fernschreiber problem.
In the meanwhile, does anyone have an idea to make carmenfdezb 's solution stay? Thanks for any help!