"Length limit reached" in a conversation with 2200+ messages

I have an Expert conversation with over 2200 total messages on the website and I just got this message when I try to send a message with reasoning, but not without reasoning. The conversation has around 4.5 million characters, so I think I just used the entire context window (1 token = ~4 characters). Its a shame they don't just cut off the oldest tokens but instead just tell you to get rid of all that context. Has anyone else experienced this?