The TACX Desktop App will not function at all without a relatively fast internet connection. I assume this is purely a revenue/licensing bit for TACX.
With so many people working from home during COVID and cable/phone/internet companies being short on staff I've now not been able to use my TACX on four occasions due to lack of internet (and per other thread I lost data from two workouts when I lost internet during a workout) or fast enough internet. I also tried using the hotspot on my phone but that was apparently not fast enough - which doesn't make sense as a license check should be an extremely small transaction.
Other than licensing/revenue protection for Garmin there is no critical need for an active internet connection. Live competition stuff obviously wouldn't work but that's far from critical.
Garmin can easily have each license check good for 30 days (or even 10 days if they really want to be ...). This especially for people who have and have had automatic payments.