That may be because the hostname can't be resolved.
https://forum.suse.org.cn/t/topic/12280 (Chinese)
https://bugzilla.mozilla.org/show_bug.cgi?id=1296836 (upstream report)
this post was submitted on 25 Jul 2024
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If you try to open FF using the terminal does it give you any error messages?
Good suggestion. What does this mean? [Parent 4226, Unnamed thread 762a7e8fd280] WARNING: Failed to set scheduler settings: Operation not permitted: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:187
(firefox:4226): GLib-CRITICAL **: 20:17:36.507: Failed to set scheduler settings: Operation not permitted
From the what I have read it seems like this is a Gnome error causing problems for software.
You might be able to get better feedback if you post in one of the Linux specific communities.
Try changing away from Ubuntu to something better, like Mint