Pfp of someone who blocked me showing up in DMs

I am looking everywhere for answers but have not gotten a 100% guaranteed answer. My ex blocked me on instagram. Their pic in my DMs turned grey after about a day. But over a week later their pic showed up in my DMs even though I am still blocked. Now their profile pic is always in my DMs basically. Does this mean they unblocked me temporarily? Because my understanding is when they block you they go grey in about a day. But my exes pic is not grey in my DMs.