Nope, you are getting your history wrong. Zyklon was developed by Degesch (Deutsche Gesellschaft für Schädlingsbekämpfung) (Currently Detia-Degesch GmbH). They later sold it under the name Cyanosil.
Zyklon B was made in America by American Cyanamid, parts of which are now controlled by BASF, and other parts by Pfizer and Proctor and Gamble.
But I don’t see the Bayer links you assert.
"IG Farben had bought the patent for the pesticide Zyklon B"....
The current main successor companies are AGFA, BASF, Bayer and Sanofi.