Phantom VPN vs Mullvad VPN

I am not sure how to fix this. I've been using Mullvad for a few years and never had a leak when using the app. I just changed computers and installed the app and got this leak result. Is there anything I should do? I tried to do an internet search to fix this and I simply get confused reading all the "DNS speak" that is all over the internet- I just don't understand it which is why I purchased a VPN service with an app that is just supposed to work

It is a bit pricey compared to the competition (lots of VPNs out there that cost ~$3/month) but apparently Mullvad is the VPN provider for this offering, and they cost $5 a month because they are considered one of the 'best' VPNs in terms of privacy (for example, they will accept cash payments: https://en.wikipedia.org/wiki/Mullvad#Privacy ).

Talking about Express and others, Mullvad have the best speed during my personal experience. (I tried paid subscription to Ghost, Express, ProtonVPN and Nord.)