Some new MIB counters are going to be added to track the fallback cases, see [here](https://lore.kernel.org/mptcp/5a78b3e0fc95d2f6356ff4754ec3bdf1dcf6b2cc.1751700000.git.pabeni@redhat.com/) (**warn**: WIP, a new version is expected). It would be good to track these counters and check if they don't have unexpected values in our tests with fallbacks (or reset, or none of them).
