The captcha where you slide the puzzle piece into place I’ve found is a much better user experience and presumably achieves the same goals (minus helping train image recognition). It’s a little bit ugly/looks like one of those spam interactive banner ads but I wish more sites used it anyway if they need protection.
"Slide the control to complete the picture". I interpreted it the first time as looking like the old iOS slide-to-unlock convention: "Once I slide the control over, it will complete the picture correctly." Now, this may be a well-intentioned accessibility thing, but it wasn't obvious that the slider was connected to the puzzle piece in the same way.
This was reinforced by the fact it was a bit janky on my entirely overkill rig, so the puzzle piece was moving out of synch with the slider until after I had overshot and failed the CAPTCHA.
I always wondered if we had much hard data on both the efficacy and the necessity of captchas. If you're not selling 3080s, you probably just need the most minimal deterrence to auto-scrapers-- the old "seven + 4 = " CAPTCHA probably does enough at a very low processing and accessibility cost.