I noticed in this Google PSI FAQ written for a previous deprecated version of the test that it says that changes made to the website do no effect the PSI score immediately.
"The speed data shown in PSI is not updated in real-time. The reported metrics reflect the user experience over the trailing thirty days and are updated on a daily basis."
https://developers.google.com/speed/docs/insights/faq
Does this part of the FAQ still apply today? I've noticed that if I reduce the number of DOM elements, the "Avoid an excessive DOM size" complaint in Google PSI immediately shows the correct new count of DOM elements but scores still remain in the same range.