A QR code is simply a fixed encoding of data, most often a URL. If the URL changes, the QR code must be updated. There is no magical way to make a data change update a QR code, at least not in a publication tool such as InDesign.
There may be more elaborate QR code management tools out there, but I suspect a lot of what users call 'dynamic' simply means the back end tech (how visits to the URL are managed) is what changes, which has nothing to do with the code once generated, or updating it.
In any case, ID does not support any form of 'dynamic' QR code. If you need the content/link to change, you must update it to generate a new barcode. If you need different things to happen from a particular URL (such as one with embedded ID data), that happens at your web/server end, not in the document or other display of the code.
— | Word & InDesign to Kindle & EPUB: a Pro Guide (Amazon)