Long-running joinmarket-clientserver makers can end up with an expired fidelity-bond certificate.

The certificate is created when the maker starts and is not refreshed while it keeps running. It expires around the next Bitcoin difficulty adjustment (so lasts at most ~2 weeks). After that, takers still see the maker, but treat its bond as having zero value. The maker can continue CoinJoining; it just loses the selection benefit of the bond.

The workaround is simple: restart the maker after each difficulty adjustment.

JoinMarket NG makers are not affected, because they generate a new cert each time.