I know that pilot used nightfighter in daylight flight (ex: Bf 110 G4 without their exhaust flames cover but still with their radar => easy to put off flames cover but not the radar). And some daylight fighter were used as nightfighter too. About the He 219, documents says that only 268 were built. Maybe some were used as daylight fighter to try to stop american bomber. But I thing it must be really rare.
According to some historic information 294 were constructed and 268 eventually put in service. A very rare aircraft. Some were put into combat service but only a few
were "serviceable".
For example, in January 10, 1945, 1st Squadron of Night Fighter Group-One had 64 He-219s on strength, but only 45 were serviceable.
The situation was so bad that the He 219 service manuals even included a special section on how to salvage crashed airplanes. Because of the Luftwaffe's desperate
need for the night fighters, and because the He 219 was easy to assemble, six additional aircraft were actually built in the field from spare parts and used operationally
without being officially registered.
Many aircraft never saw action, because they were shot-up on the ground by allied fighters strafing the Luftwaffe airbases.
I have seen many photos of these damaged aircraft. Look below for some photos
In the last months of WW2 some of these night-fighters started to have normal camouflage paint done on them. Probably done by the aircrews to make them less visible
from the sky by the attacking allies. They were usually painted in the normal Luftwaffe night-paint-scheme, but then some started to have what it looks like in photos to
be green and brown streaks painted on top. Very strange paint schemes.
Perhaps, they were also used during the day-time to stop the advancing allied troops coming from the East (Russians) or the even in the West (US an British troops).
The tremendous firepower they carried would make them an ideal aircraft to be used against ground troops also, and not just for attacking bombers at night.
These are interesting Allied photos of a Luftwaffe airbase that has been attacked, because near the destroyed He-219 you can see fuselage parts of Me-262.
Why were they keeping Me-262 fuselages in open spaces like that?
Very interesting photos.