macOS 10.14 Mojave on a MacBook Pro (Retina, 13-inch, Early 2015) Preview Version 10.1 (944.6.16)
Preview.app fails to adjust the font size of text entered in PDF text fields appropriately to the text field size:
The first screenshot is an already annotated PDF from a colleague with the last 2 text fields field added by them (with an appropriate font size scaling) and the first 3 fields edited by me, with wrong scaling. However, this also occurs on unedited PDFs as well.
Notice how it starts with correct scaling, and then glitches out, after I exit the text box.
This problem occurred even before I updated to Mojave.
This only occurred with Preview on my Mac. Adobe Acrobat displays the values with appropriate scaling.