Hello! This is meant to happen when members join your gang on Prison. Whenever a new member joins, the blocks in the mine change to average out between the total prestige levels. This also does not change if you were to kick the member from your gang or if they were to leave your gang.
When seasons reset, you will lose everything except for Ranks, Cosmetics, Tags, Skins, Perks. All other progress is reset like skycoins, money, and masteries as well as you will have to make a new island at the start of the next season.