We have confirmed with our application that this ONLY happens on Samsung devices running Android 12.
Not a single other device on the market has this problem, and it boils down to this: for some reason, Samsung is ignoring the assetlinks API response from Google, or has broken it with their changes.
How do we know? We can take two completely clean devices, an S21 and a Pixel 5, and install the application from the Play Store. We send a deep link to an email address, access it via those devices, and we see two completely different behaviors. When looking at the application info, we notice that the Samsung device defaults the option for handling links to “off” for our domain.
I don’t know if it’s because we have wildcard deep link handling, or Samsung has just plain broken them all, but we can confirm with Google’s own APIs that our app is verified to handle these URLs. We suspect, but can’t prove, it’s wildcard-specific because a non-wildcard hostname used by one of our marketing vendors is handled just fine.
Samsung needs to work VERY HARD to get this fixed rapidly or provide us with a reasonable work-around. This is ruining the experience for a LOT of applications, including some that are in the top ten lists.