All is in the title
in the numeric part of the french keyboard the dot is functioning, not with the combination maj + ";" chich is the only one directly accessible on notebooks.
This appeared with Mozilla Firefox 66 (previously it worked) and does not appear on Chromium.
When turning on the debug on the server we see that no keystrock is received/processed.
Can confirm on the latest Collabora docker image.
The keystrock maj + ";" works well with Firefox 63.0b13 (64 bits)(from ubuntu snap channel edge)
*** Bug 124749 has been marked as a duplicate of this bug. ***
This patch, posted in the duplicate report solves the issue. Thanks to Henry and Iván for working on this!
Iván Sánchez Ortega committed a patch related to this issue.
It has been pushed to "master":
tdf#124749:loleaflet: use "KeyboardEvent.key" to detect ignored key events