It's not me that says so, it's the WA that says so.
Brexit: What is the Northern Ireland protocol and why is it needed?
"If it looks like the UK is not applying EU law to the EU's satisfaction, it could impose a fine on the UK or take it to the European Court of Justice", she says.
https://www.bbc.com/news/explainers-53724381
Did you read the Internal Market Bill, part 5 para 40 onwards, para 45 appears to be the killer.
https://publications.parliament.uk/pa/bills/cbill/58-01/0177/20177.pdf