The cache logic has a bug causing ddclient to spam updates every refresh cycle.
For some users this caused bans from DDNS providers

See:

• ddclient always tries to update even when there's been no change in IP ddclient/ddclient#544
• ddclient docker image attempts DDNS update incessantly ddclient/ddclient#511
  Main issue is unrelated (see comments below), comments tbd
• ddclient spams cloudflare (and maybe other providers) ddclient/ddclient#481
• ddclient is doing spam updates every 5 minutes when managing hostnames that are proxied through cloudflare ddclient/ddclient#431