iPadOS Mail app incoming mail font size too small; "Reduced" by Apple?

Many incoming emails on the Apple Mail app on iPadOS (iPad 9th Gen, in permanent landscape position) have font sizes that are much smaller than what the sender sent. It appears as very small ~4 to 8 point font whereas the sender used a normal 12 pt font. These emails have no other content, just text.

This is definitely not the fault of the sender or their app/OS and is definitely the fault of the Apple Mail app. I tested the same email viewed on 2 different 3rd party email apps on a similar iPad and the email appears with the normal sized text that was sent. However, when viewed in the Apple Mail app, it appears as much, much smaller text. This is solely an issue with the Apple iPadOS Mail App. I did not test this on an iPhone, iOS so do not know what happens there. I assume it's not the same bug on an iPhone.

Solutions offered for this are lacking and dismissive of a very frustrating underlying problem with how Apple Mail renders and presents email to the user. Pinching to zoom in on every email received like this is not a viable solution. Increasing the universal font size in the app makes all the side and navigation menus too large to be useful.

I have the foresight and ability to not use the Apple Mail app for my personal use but this is a daily problem for an elderly relative who suffers from a TBI and can not easily switch to a different mail app. They have been using Apple Mail on iOS/iPadOS for over a decade and at this point it's muscle memory.

My guess is Apple Mail is not re-rendering the incoming HTML email, even if it's just text. It seems to be presenting the email as the same layout size and margins as it was sent in. This is CRAZY! It's 2023 and I thought rendering of HTML text to fit different screen sizes was table steaks and was solved. Apparently not for the iOS mail team.