Currently, the inlay hints are only avaiable for short handed variable declaration, but not for var。
I hope that could also be supported in the extension.
Comment From: gopherbot
Change https://go.dev/cl/677935 mentions this issue: gopls/internal/golang: add type inlayhint for variable decl
Comment From: h9jiang
This is now fixed in gopls v0.19.0-pre.2. Feel free to give it a try now or wait for v0.19.0 release.
Keep an eye on the in tools.