to my knowledge this limit existed already for a long time. it’s intented to prevent scraping and automatic bots. They basically want prevent people from using bots who act as a browser instead of using their API (where they can limit them) to do stuff on reddit.
They also have a automatic system detecting when too many clients access them with similar or “odd” characteristics (weird useragents, referers, amount of requests, weird headers in the request etc.) - if they detect such a case they usually limit you and then completly block you for hours, days or months. I couldn’t open reddit on my chrome app anymore because that as an example (i was developing an reddit client and they detected my useragent browser name as “too old”… so they just banned my browser while others worked fine )
there are bots who are able to check if a image is a repost or not and they can then remove the post if it’s a repost.