iOS Universal Link with a second level subdomain doesn't deep-link to native app, but deep-links fine on a first-level subdomain (same host)

I have capabilities in my app that contain multiple applinks: entries like so:

applinks:onepiece.domain.com
applinks:two.piece.domain.com

The first one works fine and opens the app. The second one does NOT open the app (goes to safari). My suspicion right now is because of the composite (2-piece) subdomain.

The apple-app-site-association files are completely identical on both, and are hosted and downloadable from both. Both domains are hittable from our internal network. (not publicly).

Each respective apple-app-site-association file is hosted under appropriate subdomain (not on the root of domain.com). But the same top level domain is used for both subdomains in URL 1 and 2.

Do you guys think that a composite subdomain can be the problem, or is it more likely that other network configuration differences are the problem? I couldn't find information online that states whether multiple subdomains are supported for universal links or not.

Any suggestions on how to diagnose why the second URL can not be opened as a deeplink in the app?

Should I consider uploading the apple-app-site-association file to the root of the domain? (doesn't sound completely right because that's production, and the subdomains are UAT environments. So you wouldn't wanna include UAT info in your production file...)

OR

Should I consider hosting up apple-app-site-association on piece.domain.com (only 1 level deep) instead of two.piece.domain.com?

from iOS Universal Link with a second level subdomain doesn't deep-link to native app, but deep-links fine on a first-level subdomain (same host)