Hi Justin, thanks for the report. The cloudflare-ddns version in Stable, 2.0.0, doesn't have great error handling, so it's hard to understand what has gone wrong from its error messages.
In any case, the most likely issue here is that either your network temporarily failed, or Cloudflare returned an invalid response, so the parsing failed and the program exited with an error. Everything is fine though, you can simply restart the service and it'll continue working as always (or you could even ignore the failure completely, the timer will take care of restarting it automatically). If you prefer, I could backport cloudflare-ddns 2.1.0 to bookworm-backports, since it has better error handling, and you could upgrade to that version. Thanks for using cloudflare-ddns! Glad it is being useful to you :) Bye!