Depends how you define full service. There shouldn't be a presumption that the service which operated in 2020 is the "full service" now.
Fewer services run now than in 2020, but the full 2024 service is running.
The full off-peak service in 2024 on the Portsmouth Direct is two trains an hour from Waterloo to Portsmouth Harbour, one faster than the other, and a third service from Waterloo to Haslemere.
In 2020, demand justified two faster services to Portsmouth Harbour, a slower service to Portsmouth & Southsea, and a Haslemere terminator.