I am not super familiar with the OpenAPI 3.1 specification, so please excuse me if I misunderstood anything.
It appears that tokenUrl, a fixed field, should have been modeled in the 3.1 JSONSchema as a uri-reference to support relative urls.
REF: https://github.com/OAI/OpenAPI-Specification/blob/main/schemas/v3.1/schema.yaml#L899-L901
Note that the 3.0 schema has the format as uri-reference, as I would expect.
Happy to put in a pull request if this makes sense to someone with more experience in the repository.
REL: seriousme/openapi-schema-validator#178