Cmd-tab to running zoom session randomly causes screen change

I have set totalspaces (latest version, OSX 10.14.5) so that zoom is available on all spaces. When I change from Zoom to, let’s say Chrome and then back to Zoom (I am always using cmd-tab), totalspaces always switches to a random space. Zoom is visible then, but none of the other open programs I have used on the former space.
Is this behaviour known to somebody?
Thanks & regards,