I run my own private VPN across multiple sites using Tailscale, I am trusting Tailscale, but if I were incentivised I could build out my own Wireguard VPN.
I then run Mullvad within that setup to allow me access to public VPN exit nodes and I am trusting Mullvad. And yes, I trust that they don't log me.
I can't easily replace Mullvad because I don't have servers all around the world to exit from. This is where MysteriumDark has an advantage, it is peer to peer VPNs whereby you exit from other users home or business broadband connections.
This is great as it is nearly impossible for anybody to log these exit nodes affectively as there are around 50,000 nodes online at any time and they are constantly changing.
The problem, however, with Mysterium is they recently made being an exit node a lot easier by including browser extensions, meaning you don't need to permanently run a Raspberry Pi to earn their Crypto token $MYST.
What's great for earning is not great for using as nodes come on and offline all the time, meaning as a user, your connection may be disconnected at any time without any notice.
I've noticed this happening a lot recently which is why I've mostly stopped using it as a client from my Fedora Workstation box.