The links restriction is to stop spammers putting links everywhere. You should be able to obfuscate it and post it like imgur[dot]com or something - Edit - actually i think you can just do it in a code block, just put your URL between backticks `, the forum is markdown like Joplin.
What version of Joplin are you using? Was it something that happened after upgrading?
Try running Joplin with the --disable-gpu flag. Alternatively try using the Flatpak or Snap releases; at least to test if the error occurs there too. They bundle their own versions of Mesa libraries which might confirm the problem to be related to the graphics drivers being used. Ultimately I'd presume this is a bad interaction between the newer Electron version in 2.5.10 and the drivers on the system.