I asked ChatGPT, if there are any query parameters and it returned me these:

    ?q=Hello
    ?prompt=Hello
    ?temporary-chat=true
    ?model=gpt-5
    ?hints=search
    ?hints=reason
    ?oai-dm=1

Clicking on the link will automatically open a temporary chat, with the prefilled text: "Hello"

In the past, the prompt could be sent immediately via:

    https://chatgpt.com/?temporary-chat=true&q=Hello

The parameter "q" only works without "/auth/" in the link, but then "temporary-chat=true" does not work...