leaf curl and claw, slow budding - nitrogen toxicity right?

Just to confirm - this is nitrogen toxicity right? the plant on the far left. the other 2 are almost ready for harvest, showing signs of amber tricombs.

Ive flushed it once already, with about 3 times the volume of the pot, PH 6.3/6.5 water. 2 days ago, now it seems like its doing better but damage has been done....

I plan on giving bloom nutrients again next time, will it survive? It started flowering a month later then the sweet tooth, its a Sativa: CBD silver haze. No bud formation yet. It happened in like 1-2 weeks time. Should i give it some epsom salt or cal-mag as well? or quit that too? any other tips would be helpful. Thanks all for your time. This is my first grow btw. be gentle =)

Could it have been ph?

I've been keeping it around 6.1-6.5. soil base. if it is pH, what should i change it to? 7?

Sounds like your ph is okay then. Soil tends to buffer the ph automatically anyway, so of you're anywhere near the reasonable range, you shouldn't have any issues. I grow in coco/peat/perlite/worm castings mix, and shoot for 6.2-6.5 ph with no issues. Overfeeding can lead to nutrient/salt buildup and cause all sorts of issues though (including ph swings in the root zone). Regardless, I'd just switch to a light feeding of only flower nutes, which should have little or no N.

Many sativa dominate strains are picky feeders, I think you're just feeding too much. I'd give em straight water the next 2 times.