Message request notification؟؟

I had a long Instagram chat with someone, and I blocked and unblocked this person more than 20 times. I am completely sure that I never deleted the conversation.

Suddenly, the chat disappeared completely. After about 40 days, it suddenly reappeared in my inbox, but as a Message Request, showing the message “Do you want to accept the message request from [name]?” even though there was no new message from this person.

When I opened it, the entire old conversation was still there, including all the previous messages and the custom chat theme we had set before. The strange part is that I had been searching for the chat every day during those 40 days, and it never appeared.