It’s always a treat to experience an online service that simply can not deal with logging in from different devices. I mean, Zwift does… What they do is lock the account… even though you use the provided exit functionality. So there should be something lodged to differentiate between sessions and / or devices. That lock runs for like an hour, which you won’t be told - you just get treated to a generic “problem with the account” when you attempt to login. Nothing about how long the lock will be - that would be… helpful.
I mean, basic online account handling. The sort of thing developers had to solve over 20 years ago. Reinvent that wheel, Zwift!