"Quality" = You live with a larger file size.
A scanned image brought into PDF and processed to be PDF/A compliant does not necessarily mean the file size is "too big". The point of PDF/A is to provide "forever" usability. & ya know ... that's kinda sorta just what one wants if there is interest in deployment of end-user "usable" PDFs that have textual content provided as a scanned image.
An alternative is to use Acrobat PRO to save the PDF such that it is no longer identified by Acrobat as PDF/A. Then use what used to be called "clear scan" to replace recognized images of characters with an actual font family character. Work with a copy of the source PDF. Once the clear scan process is done do Save As. Then export to TXT, RTF, DOC or DOCX.
Use the exported file to do needed clean up (much easier with a word processor rather than with Acrobat). Once this is done output a fresh PDF. This PDF's file size will be smaller.