I’m not sure how many EA/RD schools require a midyear report or how it’s handled via the common app, but my daughter had several schools accept her after her ED acceptance. She had withdrawn all apps through their portals where possible and never requested any additional information be sent. But some school still sent her acceptances (including Vanderbilt and University of Richmond - so not just big publics) She was up for big scholarships for those so applied early, so not sure if that impacted anything.
Just saying, I’m not so sure whether the high school was at fault up until they sent final transcripts (which obviously would have been required to actual accept a non-ED school) based on our experiences with acceptances after ED. But do agree that this is probably a case of repeat offender high school not a one off problem.