I have no idea how you are triggering that.
Are you on master at commit e0167310220aa7904cef8bb5454ef106cb3eecea ?
What version of rust are you using (rustc --version)? Is it 1.74.0?
Does Cargo.lock show it has locked tokio to version 1.34.0 ?
The error indicates that tokio isn't configured right.
tokio has to be built with the unstable flag.
There is a file ".cargo/config" which sets this flag.
If you set RUSTFLAGS you will clobber this setting, so you have to add "--cfg tokio_unstable" to RUSTFLAGS if you override it.
Gossip has a Cargo.lock which fixes in place the versions of all the dependenices so you can't be running some new tokio that breaks.