ITC risk when supplier GSTIN cancelled prospectively - Belagavi case

• I'm a student researching practical GST compliance gaps. I pulled public data and found a Belagavi-based food manufacturer, Nile Agro Foods (GSTIN 29AAECN0546R1ZV),
  whose registration was cancelled on 29-02-2024.

        Suppose a buyer received an invoice from them after that cancellation date (say March

2024) and claimed ITC on it. The buyer did not know the supplier was cancelled.

• My question:

  1. In practice, does the GST portal block that ITC automatically in GSTR-2B, or does the buyer only find out during scrutiny/audit?  
  2. What exactly happens to the buyer - do they receive a demand notice? Is the ITC reversed with interest?
  3. I've read the Karnataka AAR in Nandini
     Enterprises (KAR ADRG 06/2019) that says
     ITC must be reversed when the supplier's registration is cancelled. Does this still hold after recent High Court judgments on retrospective cancellation? (I know this cancellation is prospective, not retrospective.)
  4. Most importantly: Have any practitioners here actually seen a client lose ITC because their supplier's registration was cancelled, and they didn't know? How common is this?

Thank you for sharing your practical experience. I'm trying to understand if this is a real pain point or just a theoretical risk.