The Tacx Training app has been showing this issue on my Galaxy S10+ (running Android 10) since a few months (it has happened after an update) and the following updates did not solve the problem.
Currently I am using version 4.51.5.
When on the dashboard page the scrolling becomes very choppy and a lot of frames are dropped till the playlist section is passed by scrolling downwards. The choppiness appears again when you go up in the dashboard and the playlist menu is rendered again.
I have tried to contact Tacx support at their email address to report the bug but I have received an automated reply that there is no mobile app support team at the current point in time.