Everything running in a browser is sometimes a challenge when it comes to conflicting keyboard shortcuts between browsers and terminal applications. Luckily the ChromeOS terminal is quite configurable.

Hit ´´Ctrl+Shift+P´´ to go to settings and then paste the following in “Keyboard bindings/shortcuts”

{
  "Alt-187": "PASS",
  "Alt-189": "PASS",
  "Alt-219": "PASS",
  "Alt-221": "PASS",
  "Ctrl-Shift-W": "PASS"
}

Thanks to this Reddit post for the hint.