Thank you very much for your replies! very helpful.

Now the question would be what can be done to offset such difference or extra due tax ... my best guess is to continue beefing up the 3-Seule to the maximum or even pay an even greater amount into the 2-Säule...

Shall I be concerned throwing money at the 2-Säule? paying the known "gap" meaning if the bank holding the 2-Säule goes bankrupt then I lost all or?

The "filling the 2-Säule gap" strategy would only work for a year or two though because once the gap is filled I am back to square one ... any other ideas? e.g. move away from Zürich to e.g. Thalwil? or rent a 1x1 sqr meter room in Kanton Schwyz or in some cave in a mountain and still live comfortably in Zürich how many rich dudes do

Thanks in advance,
Best regards