One of the key points from #30240 is:
Saved module caches do not interoperate well with version-control and code-review tools.
This point is further developed in #30240 (comment).
Raising this issue as a placeholder for the discussion about this specific point, because this point has a life well beyond and decisions on vendor and is relevant (by and large) to all users of Go.
Please add to/edit this description as required - this is just a placeholder