The problem with reducing XP gained for a period after being defeated is that players could just sit-out the period if it was based on time.
We could hit them with an “XP Down” status effect which you need to “work off”. For example: 50% XP until you’ve earned 1000XP.
But we’d likely need to make this proportional to your current level to make it even for Lvl 1 and Lvl 50 players, so it’d become:
XP Down status effect to 50% XP until you’ve earned 5% of your current level XP.
But isn’t this identical to a straight reduction in XP?
We can add “Luck Down” and “Stats Down” to the Defeated Status effect.
If it was play time based (like other status effects) then it encourages players to “wait out” the status effect.
In general we make the assumption that Lvl 1 players are mining + killing for lower XP, whereas Lvl 50 players are mining + killing on harder worlds for higher XP.