Calendar sync issue?

Hell, I used to sync my trainerroad calendar with my apple calendar. I am starting my 22-season tomorrow and noticed that no workout has synced. Looking at my apple calendar there is a small triangle next to trainerroad and if I press on it I get:

The connection to the server “” is not secure. Do you want to continue syncing this calendar?

Any ideas why that is? In principle I don’t care about my workouts being intercepted, but I am wondering if trainerroad also fetches other entries from my apple calendar?

Best to email for issues like this.