If the DE is being held and still makes the tackle, is it a foul? Generally, no.
Had a play this season where U had holding on A63, R had holding on A73. Assessed one.
At halftime HL says, "Wow, two flags for holding and neither saw the face mask by B33?"
HL's explanation for not throwing the flag for the FM was he had drifted downfield with his receivers and felt he was too far away to throw the flag, and assumed one of the flags was for it anyway.
--Throw it, can always pick it up. If at a distance, get closer then toss.