I visit https://apache.matomo/index.php?module=UsersManager&action=anonymousSettings&idSite=1&period=day&date=yesterday and it says:

An unexpected website was found in the request: website id was set to '10' .

The GET request is initially correct

but causes a problem in UsersManager Controller:

The anonymous user used to have access to those sites...

Not sure if access was maybe not removed when the site was deleted, whether data was deleted manually, or if it is a regression etc.

We'll probably need a try /catch around this block.