I don't think anyone has worked on SimpleDNS for years.
When reported on the forum i don't think anyone really noticed the bug report neither (as that really should be done in Github).
in the 1.4.8 to 1.4.9 update it did get set to the later framework version and a new Newtonsoft.json version but thats really been the only changes to the simpleDNS project as far as i am aware.
I am not sure how that can result in breaking simpledns and would require some further investigation.
Things we did test and work on is PowerDNS, Bind and MS DNS.those are confirmed fully working incl new features such as TTL per record
Only known bug is with MS DNS and long dkim records, as wmi and ps do not pass the required line breaks which means it can't write only read long dkim records for MS DNS
Regards,
Marco