I use it in tandem with proton, so the quantity of emails going to iCloud are less, however I’ve not experienced this kind off issue with either.
Generally if a service is going to have issues with SL, it’s at the point when you provide the email that it says it’s invalid (likely due to the domain being on a black list to prevent use of the service)
Personally a big enjoyer of TravelGeek. Great comedy and very interesting topics. There is no talking though… only subtitles.