So close. What is wrong?

I’ve flushed a week ago because I thought I was nute burning.

I’m about 10 weeks into flower and want to chop soon. I’m doing 20/4 lighting. Watering 1 gallon each every 2-3 days. Any advice greatly appreciated.

Ph6-6.3 in fox farms ocean soil

2x2 tent with a cheap 1x1 light. Definitely need to upgrade. Haven’t been using any nutrients for two -3 weeks because the yellowing started increasing.

Thanks