Ignoring the first two movies?
This movie seems to ignore the first two movies, with one exception. That exception is Reggie. He is the only throw back to a previous film.
1. According to Bad Boys, Mike and Marcos had joined the force right out of high school in 1989. The film took place in 1995 and they say they had been partners for 6 years at this point. We learn from the yearbook in BB2 that they graduated in 1988.
However, in BB4LIFE, They claim they joined the PD in 1995, and still had not partnered up for Will's first assignment in 1996.
2. In BB, Mike and Marcos were Detectives. We get a closeup of the badge when Marcus holds it up to the peephole. In BB2, they were Lieutenants. We see Mike's badge close up at the pest control place. This means, at the very least, they have been Lts. for 17 years.
In BB4life, it appears they are out ranked by the AMMO Lieutenant. Given the cases they've closed and their seniority, I don't see them answering to anyone but the Captain.