The Network hash rate is calculated over a period that lags as difficulty gets adjusted. Once difficulty converges to such that block time is 60s, the Network hash rate will equal the sum of hash rates of all pools and solo miners. This is how mining works.

When for example a single miner doubles the mining rate of the pool, it will take many hours (12 to 24 or such, I don't know what is selected for XMRL) for the difficulty to properly converge.