Full season minor league affiliates will have roster sizes increased for the 2021 season, per Baseball America. Prior to 2021, all full season teams were limited to 25 players on the active roster, but that is going up as of this year.
AA and AAA rosters will now have a 28 man roster limits, an increase of three players over prior years. High-A and low-A rosters will have 30 man roster limits, an increase of five players.
With major league rosters having increased to 26 players as of last year, it would make sense that the 25 man limit in the minors would increase as well.