Generally speaking, Photoshop is not the first choice program to create Print-Ready files. However, if this is the only program available, it can produce files that are suitable for print, but extra care must be taken to ensure that the text is exported as vector shapes or live text and does not get rasterized.
The most common cause of this issue is “faux-bold” or “faux-italic” fonts, or in other words, fonts that aren’t truly bold or italic, just forced by Photoshop to look bold or italic.
This is done using the “Bold” and “Italic” buttons in the Character Panel:
Instead, the desired font style should be chosen from the Font Sub-Set menu:
This will allow the fonts to be preserved and embedded into the exported PDF.