Bittensor Mainnet // Major upgrades > Subnet Mechanisms (Previously sub-subnets) > Subnet Deregistration > Hyperparameter Rate Limits > UID Pruning What's changing // Why it matters. 1/8

2/ Subnet registration and deregistration have returned to Bittensor. The subnet limit will remain at 128 meaning that when a new subnet registers, it will take the place of the lowest performing non-immune subnet. A 4-month immunity for new subnets will allow the time for subnets to get their projects up and running.

3/ This existential threat will further incentivize subnet teams to prove their worth or make space for new builders, increasing competition and improving the overall quality of projects building on Bittensor.