I saw someone speculate elsewhere that it could be that some high-profile subreddits were hard-coded for the front page, and them going private could have crashed the system. That would be a bad implementation, but is a reasonable explanation for why everything stopped working.
I’m guessing a lot of them all at once requires all the various CDN caches to be refreshed, so higher load on the database(s)
I saw someone speculate elsewhere that it could be that some high-profile subreddits were hard-coded for the front page, and them going private could have crashed the system. That would be a bad implementation, but is a reasonable explanation for why everything stopped working.
That too! All boils down to the unexpected. Reddit back in the day was always crashing too, only really remember it being stable the past few years