It could because captchas on Plebbit are just arbitrary JavaScript, but Esteban has explained many times that this kind of captcha is useless for actually preventing spam. I found this with a quick search: https://github.com/plebbit/whitepaper/discussions/2#discussioncomment-2562316
Brave, which use it to filter it's Leo AI search, explain it very well. https://search.brave.com/help/pow-captcha
Here, you can try a POW captcha, it's very straight forward, and you don't even notice your CPU is doing some computer calculations. Usually, when it comes to POW captchas, you can change the difficulty if you want to increase the filter.
https://friendlycaptcha.com/