refresh_token_reuse
Refresh tokens are single-use. Presenting one that was already
rotated (outside the 15-second network-retry grace window) is treated
as a leaked-token signal: the whole family is revoked and the user must
consent again.
If your client crashed between receiving a new refresh token and
persisting it, this is the expected recovery path — send the user
through
/authorize again. See
OAuth §4.1.