Is this Potassium deficiency?

This is what we'd call a "Kitchen Sink" question during law school... There's a lot to unpack here, but the resolution should be fairly straightforward. First off, you'll want to flush the grow medium to get all of those excess nutrients away from your roots. The plant is likely locking out intake of nutrients due to being bombarded with supplements and enriched grow medium. Make sure there's plenty of water run-off from the flush. Second, stick to a 50% strength when it comes to nutrients at this stage. Start them off slow and gradually increase over the coming weeks. If you're going to continue using supplements and nutrients, just make sure that you're using the ones intended for Vegetative Cycle because your plants aren't anywhere near flowering yet. Third, when it comes to growing weed, less is often more. Overfeeding plants is easy, but especially if you're not growing in Coco Coir. Try feeding the plants once every 3 days to start, but you can increase frequency if you stick your finger in the grow medium and find that it's run dry at least 1" below the surface. Keep on researching and do the work. Your next grow will be 10x better, I'm sure. Happy Growing!

No I don't feel that is potassium.

I'm going to wager this is related to watering habits and the fact it gets very little light in a window sill. water entire pot. Wait for top 1" to dry. Repeat. If not following that, start doing so and your water habits were probably the cause of some sort of root zone issue. It's not about adding this or that at a specific time. The plant needs all of these building blocks all the time. So, a well balanced diet - either 100% controlled by your or a culmination of soil amendments + fertilizer - is what needs to be provided. There may need to be a tweak in flower relative to cessation of new leaf growth and stem elongation, but it's a minor effect. It's different in soil, but to give a point of reference you only need to drop N about 20-30ppm and should only be feeding it somewhere between 120-140 in vege. Still need N . It's part of cellular reproduction, among other things, not invovled with leaves and stems, too. But you learned something by adding the p/k ... relative to how you were feeding the plant was getting more than enough of it if you saw a negative repercussion from adding it. Assuming it didn't cause a ph-shift. Side note: You are in peat and perlite but also add in some earthworm hummus? i would suggest shitting or getting off the pot. Either go soilless, or go full soil / super soil and amend a well rounded diet into the pot. Don't try to straddle soilless and soil methods. With sphagnum peat, you also want closer to 50/50 mix with perlite or similar. If th ehummus is fluffy, you'd need a bit less weighted to that portion of substrate.. e.g. if simialr to coco coir, you only need 33% perlite for that sort of lower water-capacity... if it's high capacity, stick to 50/50 with peat moss+hummus. This is a small thing and nothing to worry about with current grows. Just better for root growth, therefore better for growth if you do in future. reduces risks related to root zone issues, too. soil is a learning curve. soilless you can hit the ground runnign with perfect plants day 1, if you follow the right instructions that are repeatable in any garden and most brands of soilless/hydro fertilzier as they mostly contain similar ingredients despite all the marketing garbage out there trying to make ubiquitous products unique when they aren't so unique.

Save yourself some headaches. Do some thorough research on a reputable site, like growweedeasy.com , then get yourself some plain ol feminized photoperiod seeds. They're a little more forgiving than autos for someone learning the ropes.

you do not use PK 13/14 until you are well into flowering cycle. You will probably need to flush.. use way less nutrients. Get a nutrient guide sheet of the nutrients you're using. you will also need to work on your lights.. get photone app and photone calculator to help.