Search this (
https://cis.energy.dla.mil/ipcis/Ipcis) for Prestwick and it appears that a new contract was in place from 1st May 2020 continuing to 30th September 2024. Downloading the spreadsheet and ranking the airports by contract value shows Prestwick to have the ninth-largest contract by value. That said, there has been a marked reduction in USAF transit traffic since the beginning of the pandemic with a consequent reduction in fuel sales. On the other hand, there has been between three and five USN P8s temporarily based since mid-November who are presumably covered by the fuel contract.