Hey,
I checked out your diary, you're giving too little BioBizz Grow compared to Bloom and Heaven. You should be at least at 3ml/l now. Later, feel free to go up to 4ml/l. If you increase the amount, it should improve. Right now, the deficiency is definitely very slight; your plant has cannibalized some less important lower leaves to keep the upper flowers healthy.
You're missing the basics, either N-P or K; saying which one is missing is more guessing than knowing. Your plant needs a lot of P-K during flowering, but at the beginning of flowering, it also needs a lot of N since that's when the growth spurt happens, which could also be coming from that. Definitely no Cal-Mag though.
Also, I checked your watering intervals. A little note on that:
You can definitely give more water at once, until at least 10% runs out, and do it less often. This way, you ensure that the whole pot really gets water and not just one corner dying off because nothing runs there. You can't really overwater with a single watering because the roots fill the whole pot and nothing will get stuck anywhere; the plant is too big for that now, it just drinks it all up. And anything that's too much just runs through the pot.
Watering too often, like two days in a row, can affect it since the roots will have a harder time getting air and can drown if new water keeps flowing from the top. With 20L pots and your plant size, you could probably give 4L at once.
Hope that's understandable; if you have any questions, feel free to send a PM, you can do that at the bottom right. Good luck, and don't worry, overall your plants are very healthy! 👌