When you comeback after a long time of inactive you will receive an event which give you tons of exp everyday for a short amount of time. You c*so pay a little to buy stuffs they provide you in that welcome back event.

did you skip 9 tails and he didnt ? did one of you use stam pots on mondays and the other one wasted them ? did one of you do alll dailys on thuesdays and the other didnt ?
and if youa re offline for like 2 weeks you get the Will of fire catchup for some days ... what is like half a million XP in your lvl bracked ... what sure is something but is still less XP tahn what an active palyer gets.

I think it's depend on the highest level of your server. Like in this picture my character is only lv 30 but can receive 1m3 exp per day till 20 october

ye something like taht ... or maybe the time you where away ... cause on s9 i can get like 00k ( lvl 50 char) after exactly 2 weeks ( 2 weeks is the time after taht the will of fiire shows up )