Injector issue ?

[inginerulmesterica]

Hi, one month ago i was in the service for cleaning EGR and admission intake & timing chain recall, after i took it from the service, everything was ok for 2 weeks, then a sound appear on cold (0 - 10 degrees) time, a sound like tac-tac, connected with the RPM. (on 1000 rpm the sound is like about 4 times / second, when the RPM is higher, also the tac-tac sound is faster)
Probably it is a injector sound, i used MUT3 for an SQL injectors, the sound is still here.
The sound can be heard only from outside... and the car has 102.000km, 2018 production year. Oil was changed after the sound appears, but no changes.
I checked the injectors and the no 3 look strange on the registered ID, is this normal ??? (please see the picture)

Thanks