It looks like my system stopped updating Trakt with new episodes a while back but I hadn't noticed as it's mainly "watched" stuff I keep an eye on and Emby/Trakt are correctly updating everything I watch every day.
The logs show:
2021-05-21 08:33:03.163 Info Main: Emby
Operating system: Microsoft Windows 10.0.19041
Framework: .NET Core 3.1.13
OS/Process: x64/x64
Processor count: 8
2021-05-21 08:33:04.280 Info App: Application version: 4.6.0.50
2021-05-21 08:34:41.281 Info HttpClient