There are a lot of leaves in the lower parts and in the middle area.The ones below are quite old and yellowed.Should I not do leaf pruning?We are on day 68

nope, don't prune off leaves. if they are not value-added, the plant will shed them. i would react to the progressing nitrogen deficiency, though. physical evidence of the issue vs some bro science reasons to defoliate... That plant needs more nitrogen because it is using it faster than it is supplied, hence the deficiency symptoms. as long as the red you added doesn't push DLI above what the plant can handle per 24 hour cycle, should be fine. If you were already pushing the edge of max DLI, then it might slowly cause some issues. "Max" DLI will be different for every garden. Temps, rh and ambient co2 will all make for different ceilings.