Improving the Core Web Vitals metrics does not seem to have any serious effect in incoming traffic from Google. In this example from one of our projects, impressions are up 15% (see cover photo) but clicks are more or less the same. At least the CWV charts looks is encouraging.
Does that mean the work is useless? No, probably it just means that this is the new baseline. As every other site on the web (or at least the ones active on continuous improvement) tries to also improve their CWV numbers, you also need to do the same just to keep your existing traffic.