One the 3 vet's criteria is precision: if vet warns about it, it needs to be worth looking at, i.e. "an actual problem". Having calls to now deprecated functions in your codebase is not an issue per se, the deprecation notice it's more of a suggestion not to use the function in new code. I think this new warning has the potential to be very noisy on any large codebase.

I agree with you and maybe vet is not the right place for something like this. I do however think there is some potential in a command that gives you information about usage of deprecated things.
Yes deprecated does not mean you can't use it but it does mean "sooner or later we might drop this".
Being able to proactivley look for and clean up is useful in my opinion.

Maybe it's not something that should be shipped with go and instead be a third party tool - I don't know.

staticcheck, and by extension, gopls, can check for it: https://staticcheck.io/docs/checks#SA1019

I guess the feature isn't wanted as much as I thought.
Thanks for pointing me to staticcheck @seankhliao.

Closing this.