Did you use both of them under the exact same configuration and providers
[M247 and PrivateLayer]?
Note: Mullvad uses four providers (including themselves) while IVPN uses two providers to offer Swiss servers.That's what I mean when I say I am an average user. I used them with the default configuration, so I can't really answer your question. It's reasonable that you ask though. M247 and PrivateLayer don't really ring a bell, I hope I didn't do anything wrong.
What I did was that I just opened up the VPNs and clicked on Switzerland. It must have auto-connected to a Swiss server afterwards. I checked for leaks online and it showed I was in Zurich.
You can check the provider for each Mullvad VPN server here[1]. Switzerland specific providers are here[2] - this is where you'll see that some server providers are PrivateLayer and M247.
Tip - Whenever I used Mullvad services, I always made sure that I was connected to a Mullvad owned server, even it they were from PrivateLayer or any other provider. Just adds a extra layer of comfort from my perspective.
[1]
https://mullvad.net/en/servers[2]
https://mullvad.net/en/servers?country=ch