How to prevent browser password suggestions across subdomains (e.g., ONE.abc.ai, TWO.abc.ai)? [closed]

I have multiple web applications hosted on different subdomains of the same parent domain:

ONE.abc.ai TWO.abc.ai THREE.abc.ai

Each application has its own login form (email + password).

Problem

When I log in to ONE.abc.ai and save the credentials in the browser, those credentials appear as autocomplete / password suggestions when I focus the login fields on TWO.abc.ai or THREE.abc.ai.

I want to prevent passwords saved for one subdomain from appearing as suggestions on the other subdomains.

What I’ve tried

Setting autocomplete="off" on the form and inputs

Using different name attributes for email/password fields

Using:

autocomplete="new-password"

Verified that each app has its own backend and login logic

None of these reliably prevent the browser from showing saved credentials from other subdomains.

Constraints / Notes

All apps are under the same parent domain (abc.ai)

This behavior occurs in Chrome and Edge (haven’t deeply tested Firefox yet)

I’m looking for a browser-compliant solution, not a JS hack that may break UX or accessibility

Question

Is it possible to completely prevent browser password managers from suggesting credentials across subdomains?

If not, what is the recommended / best-practice approach to handle authentication across multiple subdomains while avoiding this issue?

Are there any HTML standards or browser-supported mechanisms to scope saved credentials more strictly than the parent domain?