Indeed! It took me a few seconds to realise that it was 1.1.1.1 that's the problem. When I could connect to my favourite websites from my mobile phone (with default DNS settings) but not from my laptop (with 1.1.1.1 as the DNS), 1.1.1.1 became the obvious suspect.
It is entirely location-dependent because of how Anycast works as implemented in (E)BGP. There is no single "1.1.1.1", but many hosts that share the same vIP in many physical locations.