Version 3.0.10.1566
Mono Version 6.12.0.122
Mac OS 10.14.6
Same issue here 
In the logs I see what looks related:
2023-03-12 23:11:15.3|Info|RenameEpisodeFileService|Renaming 9 files for **[Redacted]**
2023-03-12 23:11:16.2|Error|EventAggregator|ExtraService failed while processing [SeriesRenamedEvent]
[v3.0.10.1566] System.ArgumentNullException: Value cannot be null.
Parameter name: values
at System.String.Join (System.String separator, System.Collections.Generic.IEnumerable`1[T] values) [0x00081] in /Users/builder/jenkins/wo
rkspace/build-package-osx-mono/2020-02/external/bockbuild/builds/mono-x64/external/corefx/src/Common/src/CoreLib/System/String.Manipulation.
cs:607
at NzbDrone.Core.Extras.Subtitles.SubtitleFile.get_LanguageTagsAsString () [0x00000] in C:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.C
ore\Extras\Subtitles\SubtitleFile.cs:15
at NzbDrone.Core.Extras.Subtitles.SubtitleFile.get_AggregateString () [0x00000] in C:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\E
xtras\Subtitles\SubtitleFile.cs:11
at NzbDrone.Core.Extras.Subtitles.SubtitleService+<>c.<MoveFilesAfterRename>b__12_1 (NzbDrone.Core.Extras.Subtitles.SubtitleFile s) [0x000
00] in C:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\Extras\Subtitles\SubtitleService.cs:75
at System.Linq.Lookup`2[TKey,TElement].Create (System.Collections.Generic.IEnumerable`1[T] source, System.Func`2[T,TResult] keySelector, S
ystem.Collections.Generic.IEqualityComparer`1[T] comparer) [0x00017] in /Users/builder/jenkins/workspace/build-package-osx-mono/2020-02/exte
rnal/bockbuild/builds/mono-x64/external/corefx/src/System.Linq/src/System/Linq/Lookup.cs:96
at System.Linq.GroupedEnumerable`2[TSource,TKey].ToList () [0x00000] in /Users/builder/jenkins/workspace/build-package-osx-mono/2020-02/ex
ternal/bockbuild/builds/mono-x64/external/corefx/src/System.Linq/src/System/Linq/Grouping.cs:270
at System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x0000e] in /Users/builder/jenkins/workspa
ce/build-package-osx-mono/2020-02/external/bockbuild/builds/mono-x64/external/corefx/src/System.Linq/src/System/Linq/ToCollection.cs:30
at NzbDrone.Core.Extras.Subtitles.SubtitleService.MoveFilesAfterRename (NzbDrone.Core.Tv.Series series, System.Collections.Generic.List`1[
T] episodeFiles) [0x00037] in C:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\Extras\Subtitles\SubtitleService.cs:74
at NzbDrone.Core.Extras.ExtraService.Handle (NzbDrone.Core.MediaFiles.Events.SeriesRenamedEvent message) [0x0002a] in C:\BuildAgent\work\6
3739567f01dbcc2\src\NzbDrone.Core\Extras\ExtraService.cs:152
at NzbDrone.Core.Messaging.Events.EventAggregator.PublishEvent[TEvent] (TEvent event) [0x0011a] in C:\BuildAgent\work\63739567f01dbcc2\src
\NzbDrone.Core\Messaging\Events\EventAggregator.cs:92
I wonder if this change is responsible, although that was 7 months ago. Is it possible that didn’t make it into the production release until this latest version?
More info that might help debug:
Folder structure was:
ShowName/
+-- ShowName.SxxEyy/
+-- (Video file)
+-- Subs/
+-- ShowName.SxxEyy/
+-- X_langname.srt (as many as there are subs)
This structure worked fine in the past for getting subs renamed alongside the video files into season folders, for example.