Considering that creating directories (such as user directories) with non-alphanumeric characters other than spaces, dashes, and underscores, is generally a bad idea anyway, I don't think it's too much of a priority to 'fix' - especial since fixing this issue might require rewriting a windows library file from what I saw in the thread linked.
I found a related issue on the Bedrock edition from 2015 here:
https://www.minecraftforum.net/forums/support/minecraft-bedrock-support/2501968-crashes-on-mojang-startup-screen
I'm experiencing the same issue due to a username with an exclamation point in it.
I snagged relevant details from the launcher log:
https://paste.ubuntu.com/p/XPSq9cZRCT/
I've also found the related workaround for Windows 10:
https://www.tenforums.com/tutorials/89060-change-name-user-profile-folder-windows-10-a.html
This is something that should be extremely easy to fix but has been open for at least 4 years now.
edit: the workaround above did work, effectively I had to rename the user to make it work.
Considering that creating directories (such as user directories) with non-alphanumeric characters other than spaces, dashes, and underscores, is generally a bad idea anyway, I don't think it's too much of a priority to 'fix' - especial since fixing this issue might require rewriting a windows library file from what I saw in the thread linked.
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