This is some additional information from team KODI over at their forum:
TVDB are about to release their updated scraper that incorporates that episodeguide change.
Its sitting here waiting for approval...
https://github.com/xbmc/repo-scrapers/pull/472. Should be merged in the next day or so.
I think the big problem right now is TV Rename. They need to do one, or possibly both of the following:
1. Update their episodeguide because they are using an old XML version that we don't use anymore (at the request of TVDB), and will become broken as soon as TVDB shut down their v1-3 API's.
Honestly, TV Rename should have updated this within the last two years. Read more here...
https://kodi.tv/article/thetvdb/ And to be KODI compatible, it now needs to use the new JSON format episodeguide.
2. Provide a setting to prevent the episodeguide being written to the tvshow.nfo.
If you are exclusively using nfo files always, then the episodeguide is not needed, but because it is your nfo files, Kodi runs a check on it.
So if you have any contact with TV Rename, please advise them of the above. I am happy if they contact me here for more info.
For you, because you are using TVRename and they can use TVDB for data, I would set TVDB as your scraper in KODI to match, so you don't fall foul to little, but annoying, inconsistencies between the two sites. (Wait for the updated scraper to be released).
All your previous tvshow.nfo files have this outdated episodeguide, which has been scanned into your MySQL database. They need to be removed. So your choices are...
1. Delete the tvshow.nfo file and Refresh the tv show. No need to refresh episodes if you are happy with them. (This is the preferred method).
2. Delete the <episodeguide> out of the tvshow.nfo file. Refresh the tvshow from the nfo file (really no point. Same amount of work as previous step, but for an inferior outcome) But this method prevents you adding new episodes unless you have an nfo file for the new episodes.