As we reported ... when "SoHo Karen" was charged Saturday in her attack of 14-year-old Keyon Harrold Jr. at the Arlo Hotel, prosecutors briefly detailed another incident from earlier that day in which she allegedly damaged an apartment door.

Sources familiar with the apartment incident tell TMZ ... Ponsetto entered the building by using a fire extinguisher she found to destroy the doorknob and smash her way in.

We're told a tenant of the building confronted her, and Ponsetto allegedly claimed she rented the vacant unit through Airbnb and locked her keys inside. Our sources say Airbnb isn’t allowed to operate in the building, and we're told Miya never contacted management about renting it.

Once she got in ... Ponsetto allegedly stayed for several hours, did damage to the curtains, left mail scattered on the floor and dirtied up the bathroom. We're told she also left debris in the hallway outside the apartment.

Our sources say police were called, but when they arrived they could not access the vacant apartment because the door was so badly damaged it wouldn't open ... and Miya was long gone.

Law enforcement sources tell us ... a police report was filed, and Ponsetto is currently under investigation for criminal mischief. We're told there was at least $250 in damage.

We reached out to Miya's NYC attorney, Paul D'Emilia, who declined to comment.

Of course, this bizarre incident might be the least of her worries. As you know ... Ponsetto was arrested last week in SoCal, flown back to NYC where she was charged with attempted assault, attempted robbery, grand larceny and endangering the welfare of a child for her altercation with the teenager at the Arlo Hotel.