I've found an issue with a TSA timestamp within the sigstore-conformance test suite:

• An example test is test_verify_dsse_bundle_with_trust_root
• the timestamp and payload are is in https://github.com/sigstore/sigstore-conformance/blob/main/test/assets/d.txt.good.sigstore.json
• the certchain is in https://github.com/sigstore/sigstore-conformance/blob/main/test/assets/trusted_root.d.json

I'll add a test case