Summary
Brown was a nice second-round find for the Bucks in the 2017 draft, and was able to get some decent minutes for the Bucks from 2017-2020. However, he wasn't able to prove he was above replacement-level, and the Bucks didn't have much interest in retaining him last offseason. Brown signed a one-year minimum contract with Houston, and showed some flashes this season.

He shot a career-high 42% from three, and has shown some improved off-the-dribble game. He's still finishing poorly at the rim, but he doesn't force shots there, as the majority of his attempts come from three. Brown has decent size for a wing and can defend multiple positions.

Brown may not be quite good enough to warrant playoff minutes, but I think he can contribute during the regular season, which should be enough to earn him at least a fully-guaranteed minimum contract this summer.
 
Cap Considerations
Brown will be an unrestricted free agent with a $1.7 million cap hold and Non-Bird Rights. This means that the highest starting salary the Rockets could offer him using the Non-Bird Exception is $2.1 million. This should be enough to retain Brown, since he settled for the minimum of $1.7 million to come to Houston. Alternatively, the Rockets could use their cap space or their Mid-Level Exception, if they remain over the cap, to re-sign Brown if he demands more than $2.1 million.
 
Other teams will have multiple ways to sign Brown as even teams without cap space could possibly use any of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE or Bi-Annual Exception to sign him. It's also likely that Brown could be had for the minimum.