I’m in the process of transitioning an old website to use Kirby but it’s also on an old server with PHP 7.4, so until a switch to a more modern server with PHP 8 is possible I have to resort to using Kirby version 3.7.5.3. I now have the problem that for some reason page links like page('page://on4LG9LfYqlKqYEN') aren’t generating the URL on the remote server. It works on my local server (that runs PHP 8). Does anyone have an idea what could be the reason?
Wait, so the Kirby versions locally and remote are different? UUIDs were introduced in Kirby 3.8, so not available in earlier versions.
Oops, haha, thanks for the hint; I have, indeed, version 3.9 installed locally. 
I guess I originally developed in 3.9 and then discovered that I can only use version 3.7 on the remote server because of PHP 7.4 and never thought about downgrading locally.