Steps I took:
- Took a picture using iPhone 16 Pro
- Looked at picture on MBP's Photos app
- Clicked on Edit->Markup->Text icon
- Typed the text
- Clicked on Save Changes
- Voilà -- Saw a dull picture with text
- File->Export->Export 1 Photo (jpeg, quality high, full size)
- Dull jpeg picture from step #6
The only differences when I used my iPhone 11 as late as mid-November last year were:
Step 1: Used iP11
Step 6: Picture looked the same except for the text I added on it. It didn't matter whether I edited the picture with adjustments (e.g., brilliance, exposure, etc) before or after adding the text or not even doing any editing at all but the picture always looked the SAME except for the added text.
Step 8: Jpeg picture looks like the same picture with overlayed text in the Photos app
Here's something I found out after playing around with some photos.
With the HDR is turned on in the MBP's Photos app (note: it has always been on):
- Photos are enhanced (iP11, iP16P). Of course.
- Using Markup Edit, I can add overlayed text to iP11's photo and the HDR effect remains. However, if I add overlayed text to iP16P's photo, the HDR effect disappears. Actually, doing nothing in Markup Edit and just clicking on Save Changes does the same thing for iP16P's photo.

Why does the Markup->Edit->Save Changes do anything to the iP16P's photo other than any markup done if any?