The answer is AI. Amongst other things. Reddit is about to go public and wants everyone on their main app for advertising and tracking. Twitter is dealing with hosting issues with Google.
Plus AI companies are extracting content from Twitter and Reddit to train their AI models like chatGPT which is a huge money maker, and these platforms aren’t getting any money from it so they’re trying to make it more difficult to get access to it. They want companies like OpenAI and Stability and Microsoft and Google to pay large sums of money for access to their content to train AI on.