The PDF looks perfectly readable to you. That does not mean its text has reached the reading tool in the same form. A scan may be a picture of words, and a table may lose its relationships during extraction.
Inspect one representative page
Try selecting or searching for a distinctive phrase. If it is unavailable, the file may need optical character recognition, or OCR. This is a clue rather than a complete diagnosis: a PDF can mix real text, images and imperfect recognition layers.
Adobe’s OCR documentation explains how recognised text is created from scans. Recognition is useful, but small print and poor scans still deserve checking against the page image.
Test the difficult part first
Choose a page with the kind of information you need: a table, footnote or two-column layout. Ask the AI tool to identify a specific item and its page, then compare the result with the original.
For a table, verify the row, column heading, unit and any note below it. A correctly read number in the wrong column is still the wrong answer. Do not let a fluent explanation distract from that basic check.
Keep evidence attached to the answer
Request page references and short supporting passages, then open those pages yourself. If a number affects a decision, copy it directly from the source after verification. Better extraction can reduce one kind of error; it does not remove the need to check the tool’s interpretation.