ChatGPT (developed by OpenAI) has a much larger file and text processing capacity because it runs on massive cloud server networks with larger memory limits (context windows). While Merlin AI is a third-party application built on top of models like ChatGPT, it sets its own lower file size limits (like 49 MB) my work need more MB then 49 to save on computing costs and prevent their system from slowing down. I cant even uplost my work.