I'm a big fan of VPD charts which provide temp/humidity targets throughout the growth stages. Checkout vpdchart.com.
At 81.5F air temp with a small adjustment for leaf temp, you'll get a VPD of around 1.5-1.6. That is too high. Plants will struggle to utilize water efficiently at transpiration rates that high, especially at that size.
For seedlings, 0.8 is a good target. Then 1.0 in veg and 1.2 in flower. To get your VPD down to 0.8 at 80-83 degrees, you'll need to bring your humidity up to 66-74%. This might not fix everything, but it would certainly help. A humidifier is in order. Until then, regular misting with water might help keep them a little moist...
Good luck pal!