upstream didn't build with all the dependencies at the same version as the latest in the arch repo. Nor are most upstream developers bumping all their dependency versions constantly
if you're a big player like ubuntu/debian you can go to the authors/upstream and ask them to fix the program to work with their dependency versions (in say.. an LTS release). most would be glad to bc it's just something upstream needs to do once every couple years and doesn't need maintenance. If even thats too much and yyou want esomething even more handsoff/timeless then you make an Appimage. It'll work for ever
With Arch youd need to constantly monitor the thing doesn't break?Are they just #yolo'ing dependency versions most of the time ? (itd prolly work 99% of the time..)