That is not the conclusion in the bug report.
I think it's safe to say a niche clipboard bug is not a top priority, so it may take some time for them to address it.
This usually happens when some accidentally saves a PNG file with a .PDN file extension.
Please try to rename the file.
If that doesn't fix the issue, feel free to post the file so we can inspect it.
I doubt you'll get much traction from those support tickets.
There's a Mozilla bug filed. Just give them time to address it.
https://bugzilla.mozilla.org/show_bug.cgi?id=1866655
Did you really need to post this (and to Reddit also)?
Seems like you can just send a private message to @Welsh Yellow Cheddar.
Otherwise, you're just going to have people playing the guessing game.
If the Quantize effect is not present in the Color submenu, then it sounds like you're using an old version of Paint.NET.
Settings -> Updates -> Check Now