It doesn't matter if the app works or not, some users never use the app and have constant problems with "this feature",
they better know whether to choose the app to work or their connection to work...
It ain't the user's fault - the idea of the app is it's a friendly way to access a router for someone not familar with RouterOS. But @rextended ain't wrong, it's a dangerous feature. And it only looks innocent.
/interface/detect-internet is too aggressive will
modify your configuration to add DHCP client on any interface covered by detect-internet list, if it can't ping 8.8.8.8. But "detect" doesn't imply that – docs are right on what it does. This, in some cases, may be totally fine. But adding a dhcp client can have a lot of side-effects. Another one being adding a route with a distance=1, and so your routing can get messed up, depending on what DHCP is doing and/or if your using recursive routing.
Further you have to grant "write" access if you want an end-user to be able to update Wi-Fi password. And since internet-detect is NOT protected by a policy, an end-user can change this in the app.
OK, what's alternative to have in MT smartphone app correct internet connectivity status?
I actually filed a feature request (SUP-108814) a little bit ago, since it annoying catch-22. There should be some option to stop the "add a dhcp client" logic IMO. They did respond:
We will consider adding an option for detect internet, not to create or adjust DHCP client.
If a DHCP client getting added of an interface in the detect-internet list cannot ping 8.8.8.8 isn't a problem for your ISP or cause a break in routing table, it's fine. But yeah that's a bit to unpack to know if "safe".