It’s strongly believed to be film canon. My first thought also was that it made no sense to hire a new team, but some of the leaks suggest that it takes place prior to them losing the firehouse. Business must still be doing well enough at the time of the series. Though it will be a tight fit, based on the timeline given in Afterlife. Perhaps this will be early 1990.
I’m certainly hoping for more information on the falling out between the guys. I feel it would be a big misstep if that’s not touched upon.