Apple display flickers with Thunderbolt adapter to MacBook M1 (OS 12.5.1 or 13.1)

Hello together

I have two Apple displays with a Thunderbolt connector. I connect them to my MacBook with an adapter to USB-C. That worked really well. But since I got a MacBook M1, the connection keeps flickering. I don't know when and why the flickering occurs. It doesn't matter whether I'm only using Mail or Pages or cutting films in Finalcut ... 

The adapter is from Apple. It happens with OS 12.5.1 or 13.1 and with both displays. The cables are OK.

Can anyone help me here? I'm about to throw out the Apple display here, because you can't work like that...

Than you