Nextcloud desktop client 3.4.1 does not start on macOS 11.6.3

I currently run the client 3.1.1 on macOS 11.6.3 and wanted to update to the most recent client. After installing 3.4.2, I could not start it: Clicking on the app just did not result in anything. So, I reverted back to 3.1.1, which however sometimes seem to go into overdrive and shows “the spinning beach ball of death”.