Firefox keeps resetting search engines on Manjaro

Hello everyone.
I have an issue on Manjaro KDE with Firefox where some search engines are re-added on every other launch. This issue has been discussed here before, but no solution has been offered:

I have also reported a related bug to Mozilla, where I was told that the issue is caused by the language configuration files (German, in my case).

(The aspect of the bug reported there is that all search engines are changed back to default after an update. The other aspect of the bug is that a few search engines are re-added every time I boot the computer and launch Firefox)

Is there a way to edit those configuration files so that they only change the language used by Firefox, but none of the other settings?
If not, could the Manjaro team implement the installation of those language configuration files properly? The issue does not seem to exist on other distros.

AFAIK this will be fixed in FF85 (Github-bug-list)…
On Ubuntu 20.04 / FF84 this bug is too - on Windows 10 I had this never…
The problem comes from the language-files - some flags are not set correctly in FF.
( We’ve just fixed these, so that if the language changes, we still remember the previous hidden state.
This was in bug 1675624
and should be released in Firefox 85, due out near the end of January.)
at this time - close FF with the close-gadget
use the language-file provided by Mozilla (addons) instead of Manjaro-language-file…


Thank you. I am already using the Mozilla language addon and the search engines still keep being added back in. Could you elaborate on the Close-gadget?

Firefox - top right cross like the red one: Bildschirmfoto vom 2021-01-18 16-05-45
language-file from:

Caveat: do not delete search engines, only uncheck and/or move entry to the right/bottom
(otherwise the entry comes back like a bumerang)