Some days ago, the spam protection was turned up a notch.
Well, actually, it was repaired. Two weeks ago, we found a bug that for a long time prevented edits from being throttled at all (except for very narrow exceptions).
For the record, I posted this in our internal chat room:
Thanks for proving me right :)
In all seriousness: The throttling was fixed to do what it was supposed to do all along, and not technically turned up a notch. I'm well aware that this doesn't really make a difference to the user; I'm just explaining what was going on.
and a totally unreadable captcha.
Yes, this is a problem. Both Meta and the general internet are overflowing with complaints that many reCAPTCHAs have become close to unsolvable recently. This is something we have to tackle one way the other.
In fact, wasn’t there previously a rule that once contributors had enough reputation, they’d be trusted not to be bots? Did that get switched off or am I remembering this wrong?
You are remembering correctly, for the most part. 10k users are only throttled to 10 seconds per edit (unlike the 30 seconds for lower-rep users).
Update. We have been heavily discussing this issue internally recently, and we all agree that the current state of affairs sucks big-time. Ideally a human being would never see a captcha, and if they get one after all, it should be reasonably solvable. We're discussing several routes to go, but the bottom line is that our throttling/bot detection needs to become smarter.
For the time being, we've made a change that should at least heavily reduce this issue in the particular case discussed here (submission of edits). It should now* be close to impossible for a 10k user and much less probable than now for a <10k user to hit this throttle during normal operation.
This is certainly not the end of it, merely a step, but I hope you agree it's the right direction.