Autoflower dying fast

Definitely PH related

Absolutely it's a pH issue!! Happy frog is prat dominant and it's reused? Yeah dude, your too low. The plant grew great in veg phase, nitrogen is highly available in acidic soil, but once you hit the bloom the requirements changed and that's why your seeing a consistent decline.

Moisture meters for containers? Pick that shit up and feel the weight of watered VS. dry, or go knuckle deep.
Also your ambient RH will drop when the soil is dry, the plant isn't transpiring.

Just my opinion here, bag soil is pure bullshit! Buy a bale of peat, some bricks of coconut, some bags of leaf mold, worm castings and #4 perlite or hydroton. Shit even limestone gravel would work or bullshit wood fines/mulch.

Then ammend it. Set it and forget it. Water only

Plant is already looking a bit better 36 hours after the terp tea. Appreciate the responses from everyone who didn't parrot "ph issues". My ph is fine and has been fine. Same ph as all the other healthy plants in the tent. I know how to check PH, I'm not even remotely new to growing autos or marijuana in general. I guess I just didn't realize exactly how depleted my soil was. Guy at the grow store told me some compost would bring it right back to life

Best of luck bud