There are several services like Turnstile. I'm an advisor to Ocule [1] which is a similar thing, except it's a standalone service you can use regardless of your serving setup rather than being integrated into a monolithic CDN. It's a smaller company too so you can get the red carpet treatment from them, and they aren't so aggressive about blocking VPNs and privacy modes because their anti-bot JS challenges are strong enough to not need it. They're ex-reverse engineers so know a lot about what works and what doesn't. Their tech may be worth looking at if you're concerned about over-blocking.
The mention of Turnstile using proof of work/space is a bit puzzling/disappointing. That stuff doesn't work so well. There are much better ways to create invisible JS challenges. The core idea is to verify you're in the intended execution environment, and then obfuscate and randomize so effectively that the adversaries give up trying to emulate your code and just run it, which can (a) lead to detection and (b) is very slow and resource intensive for them even if they aren't detected. Proof of work/space doesn't prove much about the real execution environment.
BTW, the author asks what proof of space is. It's where you allocate a huge amount of RAM and then ensure the allocation was actually real by filling it with stuff and doing computations on it. The goal is to try and restrict per-machine parallelism by causing OOM if many threads are running in parallel, something end users won't do. Obviously it's also a brute force technique that can break cheaper devices.