A recursive resolver stores an answer for the TTL supplied when it fetched that answer. Lowering the TTL after a change does not shorten a copy already cached with the old value. For a planned migration, reduce the TTL before the event, wait out the previous value, make the change, then restore the normal lifetime after traffic has moved.
A mixed result is evidence of a difference, not a diagnosis by itself. Check whether every authoritative nameserver serves the same zone, whether a CNAME chain has changed, and whether a previous NXDOMAIN answer is still under negative caching. The DNS lookup shows a focused answer, while the MX lookup expands mail exchanges and their addresses.
What a two-resolver check cannot see
Cloudflare and Google operate large anycast systems, but each result here still represents that provider's recursive view, not a labeled city or country. The checker does not query residential ISPs, enterprise resolvers, browser secure-DNS settings, or the cache on your own device.
If both public resolvers agree while one user sees the old destination, clear only the relevant local cache or wait for its TTL. Repeatedly changing the authoritative record during that period makes the evidence harder to interpret and can extend the apparent transition.