The IP address does not match what Tor shows. Also when I perfromed a new tor circuit Tor shows a new IP but the IP address remains the same
installed Tor sha256:44db138fcfc73f5d049488eeb580aaa79d2037b5bb2b3f8303de2b92453f55a2 and then updated tor to the current version.
I’ve been able to replicate this result with reddit’s Onion site. In fact right now I’m getting a variety of rate-limit responses from it; 429 errors, a (broken) CAPTCHA - see screenshot below - and the response you reported with the 54.87.140.240 IP address. This IP address is reported regardless of exit node, as you observed. I can still access reddit.com, although that is rate limited with 429 responses sometimes (this is normal).
My guess is this is either bad configuration by reddit and/or the IP address reported is maybe where they host their own DDoS service and DNS is resolved there. In any case it seems to be a reddit-specific thing which they’ll need to fix.