v6.0.9 - ERR_PNPM_PNPM_ENGINE_IDENTITY_MISMATCH

Context

This PR,

• https://github.com/pnpm/action-setup/pull/267

and the associated release,

• https://github.com/pnpm/action-setup/releases/tag/v6.0.9

Creates a regression on my workflows.

Details

I am using PNPM action on central workflows that without providing any with: version due to respecting each project's package.json:engines and package.json:packageManager versions,

since its setting up for 11 at first, then downgrades to 10 for instance

Switching pnpm from v11.7.0 to v10.XX.X...

And in case this extra detail needed, I am also giving the pnpm scope to public npmjs registry via npmrc instead of my private registry due to binary package limitations and so on.

@pnpm:registry=https://registry.npmjs.org/

Until 6.0.8, this setup was working but with 6.0.9, I get

[ERR_PNPM_PNPM_ENGINE_IDENTITY_MISMATCH] Refusing to run pnpm@10.XX.XX: its npm registry signature 
could not be verified (pnpm@10.XX.X: pnpm@10.XX.X has no registry signature). 
The bytes selected by this project's lockfile/registry do not match a published, signed pnpm release.
This can indicate a tampered lockfile or a malicious/unreachable registry. 
Set `pmOnFail` to `ignore` to skip the version switch if this is unexpected.

Any ideas?

Start by comparing v6.0.8 with v6.0.9 and reviewing the linked pull request #267 and release notes. Reproduce the workflow that uses package.json engines and packageManager without a with: version setting, including the npmrc registry configuration; done means the version switch completes without ERR_PNPM_PNPM_ENGINE_IDENTITY_MISMATCH.