Unexpected `.` in generated file names results in `buf` warning

When using the plugin v3.21.2 through buf on Linux (Ubuntu), I'm getting the following warning:

Warning: Generated file name "./some/path/to/file/my_message_pb.js" does not conform to the Protobuf generation specification. Note that the file name must be relative, use "/" instead of "", and not use "." or ".." as part of the file name. Buf will continue without error here, but please raise an issue with the maintainer of the plugin and reference https://github.com/protocolbuffers/protobuf/blob/95e6c5b4746dd7474d540ce4fb375e3f79a086f8/src/google/protobuf/compiler/plugin.proto#L122

...which is rather self-explanatory. I suspect this might be because of the . at the beginning.

The buf command I was using is the following:

buf generate /path/to/protos --template buf.gen.yaml -o /output/location

(i.e. I used full path for both - input and output paths)

buf generation template is

version: v1
plugins:
  - name: js
    out: .
    opt: import_style=commonjs

I tried changing out to not be . to no avail.

There are no warnings when plugin is used through protoc directly, but I think the buf is right that returned file path should not have . components.

Reproduce the warning with the shown buf generate command, buf.gen.yaml template, and plugin v3.21.2 on Linux, then compare the generated path with direct protoc output. Trace the plugin output against the referenced plugin.proto generation specification; done means buf receives a relative filename without a leading "." component and no longer warns.