Illustrator reverts text typed inline to default size and style

I've been noticing that text which I add by typing into existing text will sometimes revert to the default font size and format. For example, my default font style and size is currently regular 12-point. Let's say I open an existing design with a text object at condensed 15-point and want to change it from "This is an example" to "This is a sample example". I first use the type tool to place my cursor between the letters of "an", then start typing. Whatever I type will be added in at 12-point regular. Shouldn't newly typed text take-on the existing style and size at the point of insertion?

I had previously thought that subsequently-noticed awkward font style and size changes were my mistakes, perhaps the result of neglecting to paste without formatting. The discrepancies were usually very subtle, such as a change from semi-condensed to regular or from 11-point to 12-point. But, I recently noticed the issue occurring immediately after it happened and could reproduce it. Unfortunately, I was pressed for time and could not focus on it at the moment. Then, when I tried it again, I could not reproduce it. However, I did some digging and discovered typed changes from 18 months ago with the same issue: anything typed-in changes style and/or size.

Though I have not yet been able to test it, I do not believe the font family is affected by this issue, just the style and size. I recently replaced my Windows 10 computer with a new Windows 11 computer and noticed the behavior existed both before and after the replacement. So, the hardware, OS version, and specific installation are likely not causes. I have noticed the issue occurring in legacy documents as well as new documents. So, document corruption is likely also not a cause.