The buy-in obligation in some rare cases applies a higher minimum buy-in at cash games and Zoom tables. It applies only at high-stakes cash tables (NL/PL) and all Zoom poker tables.
The buy-in obligation limits the number of times a player can leave tables after winning money, only to re-join other tables with a smaller stack size. You can only re-join 8 times during a 20-hour period (4 times when playing Zoom), If you break this limit, the buy-in obligations will be activated, and your minimum buy-in will be replaced by the stack size you left the previous table with.
Buy-in obligations apply to all tables with the same range of buy-ins (measured in big blinds) that players can sit at the table with. For example, obligations created at a $0.05/$0.10 (40-100bb) NLHE table will also apply to a $5/$10 (40-100bb) PLO table. However, obligations created at $0.05/$0.10 (40-100bb) NLHE tables will not apply to $0.05/$0.10 (100-250bb) NLHE tables. Instead, 100-250bb tables will have their own buy-in obligations.
The aim of this feature is to reduce table breaking and discourage players from moving too many times, focusing players on playing poker rather than constantly looking for new tables.