Putting a URL directly in the video is a fast track to getting shadowbanned or just having your reach killed by the spam filters. YouTube is very protective of its Shorts feed.
Also, as soon as viewers see a blatant ad scene, retention drops and the algorithm stops pushing the video. If you want this to work, make the product scene look like organic, viral content, and drive people to the link in your pinned comment or channel bio instead of putting it on the screen. The 9:1 ratio is a good safety net, but the execution needs to be seamless.