After the abrupt stop to the 2019-20 season due to the COVID-19 pandemic, the NBA had elected to create a bubble for its players in Orlando. That was largely viewed as a success, and the NBA was hailed for how they handled the safety of their players. This year, the NBA didn't elect to do a bubble; rather, the league chose to create strict contact tracing protocols in order to maintain the safety of their players.
Recently, there was a game where the 76ers played with seven active players: now, there has been the first COVID-19 related delay of a game. Shams Charania reported that the Boston Celtics-Miami Heat game has been postponed.
The Boston Celtics active roster is also thin: they had eight active players due to the contact tracing protocol. Now with the Heat player returning the inconclusive test, it makes sense for the game to be canceled, to keep everyone safe. This was a hyped matchup between two Eastern Conference rivals: it will surely be rescheduled soon.
With the NBA not electing to do a bubble, it is possible that more cancellations are on the way as COVID-19 cases rage across the country. If this continues, then the NBA will have to find a way to make changes and adjust, but the season is far from being over.