Need AC repair help

[waheri3]

The AC turns on and I can hear the fan blowing, but the air coming out of the vents isn't cool.
Worked fine last year, but this year it's having issues.

We opened up the AC for the first time since we bought the house, and pulled out a filter that installed backward and also completely black.

Already tried replacing the smart thermostat with a dumb one, but it didn't help.

Other settings:
The house is currently reading 30C, FAN is set to Auto (other options are CIRC/ON), and I've set it to HOLD 21C permanently.

Anything else I could try or should I call an expert of AC repair in Austin?
Does anyone have an expert they want to recommend