Indeed they use the Migros Fx rates updated each day. Like each "Bank - rates"they're worse than the interbancar one. It's still one of the best credit card to be used abroad as most of other ones will even apply a surcharge for payments in CHF abroad. If you're looking for a better credit card to use abroad you can check UBS Key4(Mastercard exchange rate + 0.5% surcharge). For swiss debit cards the best one remains the one from Neon (Neobank with swiss Iban) that uses Mastercard exchange rate.
If you're looking for the best Fx rates and lowest fees you should consider Revolut but beware that they don't have a bank license.
Hope this helps
https://help.revolut.com/help/more/l…evolut-a-bank/
Sadly only in the EU at the moment. Revolut in Switzerland follows the UK entity. But hopefully they should acquire a license in the upcoming months
Big deal.