I’ve just had the Jet2 ad blocking the navigation buttons at the bottom of the page on https://www.mumsnet.com/talk/womens_rights/5302114-trump-team-to-stop-family-planning-funding-as-it-reviews-whether-its-being-used-for-dei-programs
After a few seconds the X appeared in the top left corner of the ad, but it’s hard to see & I only found it because I knew what to look for.
I’m on an iPhone 13 mini using Chrome.