In need of advice

Hello my fellow plant enthusiast.

I'm encountering some problems with my White Widow plant. It appears to have stunted growth, and the leaves are turning yellow. Additionally, I'm dealing with a significant thrips infestation. I initially tried treating the plant with neem oil, but it had no effect. Next, I plan to use mite sachets.

Here's a timeline of the plant's growth:

Planted on 25-8 in a 20-liter pot. Soil composition is 70% peat and coconut coir, with 30% worm compost. Started the 12-12 light cycle on 9-10, around the time I noticed the first signs of yellowing tips. I raised the light, suspecting light stress. During the growth period, I provided a significant dose of nitrogen, switching to a phosphorus fertilizer when flowering began. Could I have overdone it? On 23-10, I watered the entire pot to encourage runoff, and I repeated this on 26-10.

I'm seeking advice on the possible causes of the yellowing leaves/tips, how to combat thrips effectively, and any other aspects I should consider. Your expertise would be greatly appreciated.