Mullvad VPN was used on 2018, there were a lot features missing which are now, most important RAM only driven servers, earlier there were some minor logs collected, not IIP.
They did not get logs information from Mullvad, they got logs from servers which he connected to with Mullvad (law order to get servers on hands, disks were strongly encrypted and password protected but they managed to uncrypt), then they collected dates and times.