Ah yeah that's something we want to fix. If you're signed in it keeps the report around but if you're signed-out it's stateless. It's definitely on our to-do list to fix.
This is sort of representative of web.dev vs the rest of Google.
Read the rest of the comments, seriously. I would be very discouraged to release this web site when the rest of the company is vehemently opposed to any of the practices listed there.