I just discovered that Kopano DeskApp is contacting a server that is owned by google everytime it is started (18.104.22.168). It transfers 13,5 kB of encrypted data via port 443 (server side, GQUIC). The hostname to that IP address varies, one of the hostnames of the contacted IP address is consent.google.com.
After some research I believe DeskApp is based on Chrome/Chromium - that might be an explanation. But I have not been asked if it is ok to share data with google, I have no account there, I don’t want Kopano DeskApp to contact Google and I want to know what data is transferred to them. Does anyone know details of this transfer and why there is no information about this?