What makes you think it's a lockfile issue? If they sighted a patch upgrade then updated the lockfiles but then noticed a breaking change, then lockfiles are irrelevant.
If it's actually like they claim, I understand the frustration. (Not that I know this project in particular or how it gets integrated.) Without clear versioning and/or changelogs/release notes managing upgrades is cumbersome, sometimes impossible.
In some cases I've had to ask for clarification in PRs because release notes were not clear, PR was not clear, and resolved ticket was also not clear on the thing or solution.
Apparently they had issues before, so maybe they could have expected "patch may not be patch-only".