Can this also be implemented for the desktop/web version of ProtonCalendar?

IT IS IMPLEMENTED, FOLKS.
In the Calendar app, go to Settings, then Time Format (the fifth setting you see in the list, the one before last - as of 2021-08-02 at least). Then you can choose 1. System default; 2. 13:00; or 3. 1pm.

Just came back and saw the comment on how to activate this. The option should be more apparent as I looked and couldn't find it until someone explained where it was.

ISO 8601 uses the 24-hour clock system.

Hello,
This is already implemented. When you go to settings, click on the Account/Dashboard button on the left. Then find the section "Language & Time". There you can change the time from 1pm to 13h

@gjwolfswinkel, I see nothing pertaining to time under that general preferences link. Has it been removed, or moved? Do you still see it?

Is this implemented yet?? I can't find it.

@gjwolfswinkel

Yes, it seems that this has been implemented. Feature request may be closed then.

Or U.S. veterans that find civilian life annoying and aggravating.

In the General account settings, I picked the 13.00 time notation, available here: https://account.protonmail.com/u/3/general#week-start

To me it seems this feature is implemented?

Yes, I wholeheartedly agree. 24 hour clock is just better in every way. No confusion. Here in the US people confuse Noon (12 PM) and Midnight (12 AM) ALL the time. 24 hour clock eliminates this. While I understand this is a matter of choice and that most people prefer AM/PM here in N. America, there are some of us who have worked in industries that use the 24 hour clock. Once you get used to it, the old 12 hour AM/PM format seems very constraining

Agreed!

Yes please, I'm looking for this as well!
The Android Proton Calendar desplayes this correctly!

Every time I delete my personal AOL emails, they come back, I have to delete them several times before they go away permanently. Please help me, i don’t understand why deleted AOL Email reappearing in my AOL Email inbox.

https://www.talk2techguru.com/forums/topic/why-aol-deleted-email-comes-back

HI everyone what is the feature for calendar sharing so an assistant can use to see teams calendars

Would be nice to be able to enter the time of a calendar event in 24 hour format instead of being forced to pick an option with my mouse. I.E: 1700 for 5pm, 0930 for 9:30am, etc.

As a veteran I would find this easier than AM/PM format. Yes ISO 8601

Where exactly can you find this setting? Thanks

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Not just time format, but also the date format in ProtonMail (ie: 2020-12-31)
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You can change the time format in account settings (at least in the beta version).