help with using to Preview - markup on pdf creates shadows

It works using the following on Preview on Big Sur, and I expect that the same process will work on Monterey too.

1. Select a rectangular shape with a white fill color and a red outline for visual placement purposes. You can control the border and fill respective colors with the markup entities :
   1. Once the rectangle is placed where you want it, set the border color to transparent from left-most tool above. The transparency symbol is on the left of the second color row.
2. Now, insert a text box, set the font size and color from the Aa markup tool. Enter your replacement text.
3. Move the Text box over the white rectangle, and once positioned, set the border and fill colors to transparent, and that should dispense with any default border line around your text.
4. Save your work

Place the white box with its outline where you want it, and then change the outline to transparent. Do the same with the replacement text box with the same font and font size as the underlying text.

I did this on macOS 12.1 and there was no shadow present when I eclipsed original text with a white rectangle shape and text box, each with their borders set to transparent.