Hi EyalShabi, I am Paulo and I'd like to help.
Try to use the updater from the WhatsApp website to see if it'll successfully update the app. Go to this link and click on the Download link on the upper right part of the page. It'll download a .exe file of Whatsapp and it should launch the Microsoft Store and install the latest updates.
https://www.whatsapp.com/download/
(Disclaimer: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before downloading and installing it.)