We use Microsoft Teams. After booting the computer and seeing the Windows desktop, Teams pops up as a normal window after a few seconds delay. This is annoying because you might be typing something as Teams pops up.
The registry setting for launching Teams at startup is defined as follows:
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"com.squirrel.Teams.Teams"="C:\\Users\\USER\\AppData\\Local\\Microsoft\\Teams\\Update.exe --processStart \"Teams.exe\" --process-start-args \"--system-initiated\""
In Settings > General, I tried Open application in background
. After rebooting, Teams now starts completely hidden (not visible on the Taskbar), which is not what I want.