Disguise Self does not end when you are incapacitated
According to the rules on spell duration in the Player’s Handbook
A spell’s duration is the length of time the spell persists. A duration can be expressed in rounds, minutes, hours, or even years. Some spells specify that their effects last until the spells are dispelled or destroyed.
There is no mention of a spell ending early if you are incapacitated. However, under the rules on concentration it says:
You lose concentration on a spell if you are incapacitated or if you die.
Since it is specified for concentration spells, but not for other durations, it is clear that spells do not end early if you are incapacitated, or even killed
As such, since disguise self is not concentration, It does not end early if you are incapacitated