Owners who take UPI through staff — would you even know if an employee swapped your QR for their own? How do you check/prevent?

Was on a call with a friend who runs a restaurant, picking his brain before I get into this line myself. Somewhere in the middle he goes "watch out for your staff swapping the QR", apparently it's a known headache, employee quietly replaces the counter QR with their own and pockets payments. Sent me down a rabbit hole on the news cases — the Goa one where an employee swapped the shop's scanner and skimmed ~₹50L over years, the petrol pump ones, etc. What gets me is how long they ran before anyone noticed.

So for those of you who run a place where staff handle the counter or take payments i.e. you're not personally watching every transaction (pumps, restaurants, pharmacies, clinics, multi-outlet shops, delivery/field collection, whatever):

• Would you actually know if an employee swapped the QR or just showed their own phone? How?
• Has it happened to you or someone you know? How did it come to light — customer complaint, end-of-day mismatch, audit, pure accident?
• What do you do now to check, if anything — daily reconciliation, soundbox, dynamic-QR device, surprise checks, or honestly nothing?
• If you got burned once, did it change how you run payments?