I think I found another hint that the correct unit was probably 1./EJG 1:
Fw 190 A-8, W.Nr. 580400, White 2 had a very similar font type of its tactical marking.
While the aircraft is generally associated with 5./JG 4 according to online sources, it was mentioned in ULTRA reports: on 6 December 1944 it was assigned to I./EJG 1. It left EJG 1 again two months later on 8 February 1944. My theory is that the photo was taken while the aircraft was with EJG 1. It may have been with JG 4 before (or more unlikely after) it spent time with EJG 1 and that it is now generally associated with JG 4. Other Fw 190 of 5./JG 4 had white codes of a different font type and with black outline.
Roger