The official Reddit Status Twitter confirms this is a pretty common occurrence: https://twitter.com/redditstatus
The "elevated error rates" always presents as an "oops, you broke reddit!" landing even on old.reddit. I imagine since it is an "elevated error rate" rather than a total outage that it might be localized to geo or some other kind of shard. I'm on the US West Coast, though, so I can't imagine I'm in a minority.
(Which is confirmed by the number of people responding to GP.)
You'd get timeouts, and I'd never see them - despite being West Coast (Canada) as well. Or at least, that's my best guess so far.
I imagine it probably has some to do with specific geography as well. Cloudflare will proxy back to nearest node and maybe some are better than others.