Seems like the plants have faded a bit already... depends on if you are a later or early harvester i guess? Can't really guesstimate eta from pictures, so if it's got a while yet, definitely fertilize at least a little bit. Can't grow without building blocks, and that includes producing trichomes and all other elements of ripening.
Flushing is a myth. If it was necessary, we'd be 'flushing' plants outside in the ground, which nobody in their right mind would do. Leaching out all the nutes might even be detrimental to the next crop, lol. People do a lot things blindly due to faith and misguided perceptions of reality. 'flushing' before harvest is one of those things for sure. you can't prove a negative. Either you prove a measurable effect or you do not. Evidence is piled up on the 'no repeatable effect' side.
But do what makes you feel good. Just make sure it doesn't fade so far it can't cannibalize itself. No point of giving it light if it can't grow/ripen. It cannot manifest necessary building blocks just by pure will.