https://www.galleriaaccademiafirenze.it/en/news/combined-tickets-and-new-opening-hours-for-all-museums-of-galleria-dellaccademia-di-firenze-e-musei-del-bargello/
According to this website (above: one of the 'official' versions) the Accademia and Bargello group of museums were consolidated back in March, thus the ability to offer a couple of combined tickets + standardizing their opening visiting hours/days. While practically all Italian State museums (not civic or private types) are closed on Mondays, those in the current Bargello group previously had individual, wonky visiting days/hours, making pre-planning visits a bit of a hairball!
To get a look at that previous mess? The Bargello's closure days/hours were 1st, 3rd and 5th Sunday and 2nd and 4th Monday, monthly; January 1st, May 1st and December 25th, open only from 8:15-13:50, daily.
The Medici Chapels were closed 1st and last Monday, monthly; January 1st, May 1st, December 25th, and open hours 8:15 – 16:15 (November - February), 8:15 – 17:15 (March), 8:15 – 18:15 (April, May, September, October - before daylight savings time) 8:15 – 17:15 (October - after daylight savings time) 8:15 – 18:30 (June - August).
The other 3 had their own hours/closure days! So yay for Florence for making it easier to figure out some wheres and whens even if it restricts what to see on Mondays a bit more (Monday is a good day to hit some fabulous Florentine churches, the duomo's complex, Palazzo Vecchio, etc. or maybe take a day trip.)