I just read a website that says we can go back and forth after July 21st. This is undoubtedly subject to change with current conditions and remember what the US says and Canada says may differ so check with both sides before you cross over.
Interestingly, the last time I had a passport problem (expired) and could not find the answer online. I simply called the office in Friday Harbor and talked directly with an agent. He gave me the straight and current poop in a simple phone call. It made me realize how much I had gotten away from talking to people who actually run the show. Now if I can get certain people to quit texting for hours on end when picking up the phone is more expedient anyway.