Sorry for the delay in response.
Could you please confirm if there is a change in fonts or just the font size when you export PDF.
It will helpful if you can share the screenshot of the PDF file and the word file you get after exporting.
To share the screenshot, open the reply window on the forum and select the insert image icon as shown below in the screenshot.
Then click on Choose file and browse the location where you have saved the screenshot file.
Select the file and click Open > Insert Image.
Please try once to export PDF online here: https://cloud.acrobat.com/exportpdf
Check if you get the same results.
Is this issue occurs with this particular file? Have you tried to replicate the same with other files?
Did you create or edit this PDF in Acrobat?
What is the dot version of Adobe application installed on your system?
Are you on Mac or Windows?
Let us know if you need nay help.