Harvest Lock up
Harvest lockup is a creative farming rewards lockup mechanism in order to help limit the frequency of harvesting to prevent farming arbitrage bots from constantly harvesting and dumping.
For example, the harvest lockup of the POSI-BUSD farm is 12 hours. It means that farmers who stake in the POSI-BUSD farm can only harvest (claim their rewards from farming) every 12 hours.
You can check the harvest lockup on each farm card.
To clarify, the harvest lockup only locks users' farming rewards. The tokens and LP tokens staked in farms can be withdrawn anytime.