For the 404s (assuming the status code isn't a 4xx), use a URL that you strongly suspect won't exist, then you can do a comparison (levenshtein distance, bag of words, etc.) to see if it's very similar to one of about, ideas, etc. pages.
Most are a 4xx code, I checked myself, some may be 301/302 redirect to 4xx not being handled properly by their crawler
Right now it only excludes pages based on the text content: https://github.com/lindylearn/aboutideasnow/blob/main/apps/a...