Flushing at end does not in any way impact the mineral content of flower. This is not a debate.
Anything that might impact quality is about what you did over the long term and not so much what you do for a couple weeks at the end. The plant has no excretion system. It has no way to 'flush' anything out of it. If it is in the plant, it's there until it gets used. It cannot shit it out, and you cannot flush it out with excess water. This is nonsense bro-science.
Just don't overfeed it. React to toxicities before they become serious issues. No need to flush if you do that.
You have overfed, so dialing back would be wise. Maybe even some water-only irrigations. Cause to an effect, not some magic about reducing minerals in flower that was already grown, lol. The materials used to replicate those cells for growth are already there. any negative impact from nutrition provided while it grew is already hardcoded into the plant.
Just because some things have been overfed does not mean all things have been overfed. you may find you need to drawback some elements, but keep others elevated to avoid deficiencies.
Simply avoid toxicities and deficiencies and you will most likely be in that goldielocks zone. I like to find an upper threshold, then dial back from there. It may waste 'some' nutes but i know if i am giving as much as i can without buildup in the leaves, i am not short-changing growth potential.