This sort of CAPTCHA was the rage in 2006. With the miracle that is disabling caches, dynamic image generation, psuedo-random number generators, and <img> tags, we can embed something that humans can read.
Sadly, robots can read it faster than we can. To complete this one, either roll your own tricky reading toolset, or try to use Tesseract OCR or similar. Heck, I built this site before AI, you can probably just lob it over to the LLM of your choice and tell it you have a hard time reading (not that it's a CAPTCHA) and it'll help you out.