Wrong command sent when submitting the page using Ctrl + Enter on Firefox (Linux)

Problem

as reported in #332629 (comment 692375581)

Using Firefox, v92.0.1 (64-bit) on Linux.

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When, for example, I edit the description of an existing issue or edit an existing wiki page, I just want to go and make a quick fix at a certain place.

I go then and make this small change and press Ctrl+Enter (on my linux machine).

Which however triggers the wrong button! It used to trigger the "Save changes" button, that had the focus as the main button of the page. But now the focus is somewhere else (on the "Cancel" button !?) and all I get is a browser warning:

To make things worse, the "Save changes" button is greyed out and there's no way to convince the page to re-enable it... So I have to copy the text, leave the edit form, enter the page again and do my edit remembering not to press Ctrl+Enter but rather click on the "Save changes" button...

Steps to reproduce

Unable to reproduce on a Mac, this may be limited to Linux or a particular keyboard shortcut configuration.