How do you know you’re not gaslighting yourself?

Maybe the article never changed, it always read how the other person interpreted it.

You read it through your filters and took something completely different than what it said.

I’ve seen this happen heaps. Even with articles where I’ve been able to prove it hasn’t been edited, and books too.

No news sites change headlines and edit articles all the time. Often there's a "last updated" date on the article and it can be days or weeks later than the original posting date. The last-updated date is better than nothing, but without a changelog it's very hard to know what version of the article you or anyone else read at any given time.