Issues with Lambda Function URLs

I am trying to pass a huge user input from my angular frontend to my lambda using function urls. I am getting 502 bad gateway everytime I try to send the request. I tried get and post. But the same issue. Is there any word/character limit on the function urls or urls in general and what alternative can I use to get a huge input. I am able to send upto 1220 words right now but anything above that causes this issue. Can I edit any config for function urls (I can't see any options) Thankyou