A problem has been detected where Jellyfin and SageTV was causing problems with the SD-JSON service leading to accounts being temporarily blocked.
The SD-DD service isn't affected
I don't know the details on the SageTV issues, but it's similar.
12/18 Update: The block occurs after 5000 login failures in a few minutes.. basically a denial of service attack. If you disable Jellyfin's grabber and switch to XMLTV source, open a lineup support ticket, request a ban remove and include your ip address (you can get it here).
02/04 Update: The issue with Jellyfin wasn't fixed in 10.10.4 (or 10.10.5). JellyFin is still ignoring the "back pressure" responses that we send once they've hit a limit and just keep going at 20-100 requests per second.
02/21 Update: Reports show both Jellyfin and SageTV are still triggering denial of service attack defenses. To remove a block open a lineup support ticket, request a ban remove and include your ip address (you can get it here). It's a good idea to disable what's causing the problem and switch to a good data source (probably XMLTV based) while the issues are being worked.
Here's the Jellyfin github issue