Go to https://www.palringo.com/en/gb/
Click on the icon on the top right hand corner and sign in.
On the drop down bar click on your name and another drop bar will appear, then click message history.
On the the screen contacts/groups will appear click groups and then compare the groups listed with the groups listed in-app.
The groups listed on the website that you cannot see in-app are the groups you are banned in.