u/Few-Caterpillar4692

Replaying MR1/2 DX currently since Fire Red/Leaf Green dropped, idk something about it revitalized this genre for me. Anyway, I raised some decently strong Expedition monsters from MR1 and slated them to MR2, but noticed they have shorter lifespans than usual? My first one gave me the Prime warning at only 1y7m (granted, I had to enter a few battles because I was fighting poverty), but my second slated monster got the warning at 2y1m, having done only 1 battle and 1 errantry. It never got tired and stressed either. I know I've gotten that warning way past 3y+ on some breeds.

My query is, do slated monsters live shorter lives? Didn't see anything on Legendcup, unless I missed it. TYIA