pagespeed insights score jumps around every time I run it

if you're running lighthouse from chrome devtools rather than the PSI site, do it in an incognito window. extensions get loaded into the test and they move the score more than anything on your actual site.

That's normal for the lab score. Each run is a fresh Lighthouse test, so server response time, third-party scripts and ads loading differently all move it a few points either way. Run it three to five times and go with the middle number. The part worth watching is the real user data at the top ("discover what your real users are experiencing"). That's 28 days of Chrome field data and it's what Google actually uses, and it doesn't jump around run to run. If the swings are huge, like 40 one run and 80 the next, look at TTFB, it usually means caching isn't consistent.