Directly from ASA's website after 10 minutes of digging:
"If the video is largely editorial but includes a section that is advertising, or only some of the products featured are affiliate-linked products, it should be clear immediately before or at the time the advertising starts/the affiliate linked products are featured – either by way of a clear verbal explanation or prominent on-screen text to make clear which parts of the content are advertising."
So not just my opinion.
Nope, doesn't apply to the type of content people like Ali make unless the entire video is an ad.
Edit: just read here
https://www.asa.org.uk/news/like-comment-and-comply-youtube-and-the-cap-code.html
There's a clear distinction between an influencer post and a vlog that might contain a product placement ad but would stand up on its own without it. So we can all calm down now about reporting and all that. Clearly the ASA doesn't mean all UK youtubers who receive sponsorships for something should label the entire video with "ad". So that's reasonable.