Why must my poor semver be hurt so!
It is fully according to their versioning policy:
https://docs.astral.sh/ruff/versioning/
But also compliant with semver:
Major version zero (0.y.z) is for initial development. Anything MAY change at any time. The public API SHOULD NOT be considered stable.
(Maybe I misinterpreted your remark, but semver does not get hurt.)