Yes, this is happening to me too. Last time I successfully edited a Google Sheet was this morning around 8 AM, and now (6 PM) it's broken. My "storage" page shows 18.86 GB of 28 GB used, and I have no idea what's going on.
Sorry I don't have a solution here, but at least we're not alone.
Sorry I don't have a solution here, but at least we're not alone.