Yes. Cloudflare cannot access ADSB host. My VPN exit node central USA. Same result when exit node is northern North America.
Ping indicates adsbexchange.com host is up & answering pings:
PING adsbexchange.com (104.26.4.191) 56(84) bytes of data.
64 bytes from 104.26.4.191: icmp_seq=1 ttl=58 time=55.0 ms