Why is TBT on PSI so different from my local machine?

When I test the performance of my SSR SPA on localhost, I get a low TBT (total blocking time)
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When I use PSI (pagespeed insights) to test the performance of the site, I get a very high TBT

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How can I decrease the TBT on PSI? What might cause the main thread to be blocked only on PSI but not on lighthouse? Is it possible the service worker caches the main bundle and PSI doesn’t use SWs?

Can I work around this somehow?