Thanks for taking the time to share the solution you found @thetechnician!
There are many different things that can cause Arduino IDE to hang on startup as you experienced. Normally we can get some clue about the specific cause of the general fault (and thus the appropriate remedy) by examining the logs. Reports like IDE 2.2.0 hangs on startup are quite tricky because in that case the logs don't show any error at all so we don't have any distinctive symptom to identify the cause. It seems the lack of a symptom may be the only symptom we have to indicate this --hostname :: flag might be the solution.
However, your logs are different in that we do have a distinctive symptom:
From my investigations, I found the cause of this error is the system clock being out of sync. For me, and for the other users with this error I have supported, the solution was simply to sync the clock.
Since the system clock is periodically synced automatically (dependent on Internet access), I'm wondering if the problem might have resolved itself on your system and the fact that the IDE was able to start once you added that --hostname :: flag was purely coincidental.
Anyway, if the IDE is working then all is well and we don't need to be so concerned about the reasons why it is working unless you happen to find that boring subject generally interesting (as I do). I only thought I should mention it in case others discover this post through a search for the distinctive "openpgp: signature expired" message and find that the stated --hostname :: flag solution doesn't fix it for them.