That is quite interesting. I just tried my Vue login page without a form tag and am not getting that warning/error. Is [DOM] some package/plugin you are using?
I am also testing in Chrome on Linux with an Ionic Input set with a type of password without being wrapped in a form tag. I figured it out though. I didn’t have Verbose logging on. With Verbose on, I do see the same message when I remove the form tag for my Login.vue component.
As the message and SO link state, it is just a warning from Chrome so you could either ignore it or wrap your inputs in a form tag. I believe it is good practice to use a form tag especially for accessibility though.