The NBA star just listed his Encino mansion for a cool $8.5 million -- $2M more than what he paid a year ago after the Jordyn Woods drama -- and it might very well be the sign he and his baby mama are officially back together.

These digs are top-notch, BTW -- kind of the ultimate bachelor pad for the rich and famous type. It's an almost 10,000 square foot farmhouse style home with 7 bedrooms and 7.5 bathrooms, with all the bells and whistles of luxury you might expect from a home like this.

It comes with a pool, an outdoor kitchen with a bar, a spa, a foyer, a marble fireplace, a separate fire pit, a home movie theater, a twirling staircase, a guest house out back with two bedrooms of its own -- yeah, like we said ... it's got the works as far as nice stuff.

Tristan swooped the place up last summer following a tumultuous breakup with Khloe after she accused him of cheating (again) with Kylie's former BFF. It wasn't too far from her in Calabasas either -- remember, they share a daughter, True, whom they co-parent.

Keep in mind ... they've been spending an awful lot of time together during quarantine -- and they're not hiding the fact they've been hanging out ... especially around True.