Returning player: Level decay?Follow

After returning to the game after a 5 year hiatus, I noticed my main's level seems to be a bit lower than I remember it being. In this case -- level 49, though I remember hitting 50 at least, and was pretty sure I'd leveled a bit beyond that even. I've noticed this on other toons as well -- my lvl 15 necro on another server was level 13 with 0/%100 xp, which is an odd amount to have. Every toon seems to be lower level than I remember it being.

Is this a natural side-effect of account dormancy, or did they rebalance XP in a way that resulted in net level-loss?