This would possibly point to the base HomeAssistant code HIBP being the underlying issue in your situation and returning this error, and SAMBA being the package that is affected, that you have observed.
If it affects multiple users as you would seem to indicate, a trace or debug and some more info would possibly assist in having the issue resolved, or at least isolated to a specific set of circumstances, such as DNS, ISP or country firewalling, or just something unique to your configuration like docker configuration.
There’s more to this than has been documented here so far.
Update: I checked the code in GitHub and it hasn’t been changed in over ten months. There are allowances for ‘throttling’ in the code. Maybe HIBP has been getting throttled by popularity or Microsoft Azure downtime issues, or the situation is local to your configuration.
Reading return codes for throttling at https://support.haveibeenpwned.com/hc/en-au/articles/5744766972431-Why-do-I-keep-getting-HTTP-429-Too-Many-Requests-when-querying-within-the-rate-limit would tend to indicate that a check for the relevant upstream Azure HTTP:429 code has not triggered. Maybe the code that checks the header code returned needs a bit of fleshing out?
Do you have NAT issues with IPv4 address overloading by your ISP? Vietnam comes to mind, where most of the country sits behind a tiny number of IPv4 addresses.