According to Foresight News, Ava Labs Engineering Director Patrick O'Grady proposed the Avalanche subnet Astra upgrade proposal "Subnet Only Validator" on GitHub. The upgrade proposal intends to introduce a new type of staker, the Subnet Only Validator (SOV), which can validate the Avalanche subnet and participate in Avalanche Warp Messaging (AWM) without synchronizing or becoming a mainnet validator. The proposal requires SOV to pay a refundable fee of 500 AVAX on the P chain to register as a subnet validator, rather than staking at least 2,000 AVAX. The proposal intends to transition to "pay as you go" subnet validation and AVAX to enhance subnet security.