Oh man, if I had a penny for every time this issue came up, my grandchildren wouldn't have to work a day in their lives.

Try a few queries to an anycasted resolver for the same record. It's rather common that, for example, TTL values differ per response. (the magic trick here is that it's not guaranteed that your requests end up on the same resolver).

You could have a look at https://dnsdiag.org/ that provides a few tools for further introspection in the many (different) answers resolvers can give.

Would be useful in my unfortunate case where the ISP's DNS is broken for a bunch of domains. Most notably githubusercontent.com. Also a bunch of CDN domains.