Last guy put a DEF injector in 6 Mos ago. Leak looks to be from before mixing chamber under shield @ DEF injector. Injector hole is clear (no build up there). And no leakage at the injector gasket ot lines. No fault codes, just a lot of white gray smoke when run hard (only when in Regen). Could there be a DOC internal issue?
Pull the injector out and do the spray pattern test. See if it is drizzling or atomizing properly in a cone shaped spiral. Never seen that before.
You would think with that much def on the outside there would be a code for the scr efficiency being low
I've been studying your pictures It looks to me like you have def leak towards the engine and the fan is blowing it.