You can block transactions from Mastercard debit and/or Visa debit cards by creating a custom block rule in Stripe Radar.

From the Rules section of your Radar dashboard:

1. Scroll down to the When should a payment be blocked? section.

2. Click + Add rule.

3. Add the following block rule depending on the card type you want to block:

Mastercard debit cards:
Block if :card_funding: = 'debit' and
:card_brand: = 'mc' and 
:card_country: = 'CA' 

Visa debit cards:
Block if :card_funding: = 'debit' and 
:card_brand: = 'visa' and 
:card_country: = 'CA' 

4. Click Test rule to ensure the block rule is functional.

5. Click Add and enable once the block rule test completes successfully.

Note that the above rules block cards based on their card_brand as well as the card_country attributes, which is represented as the two-letter ISO country code for this country. In this case, CA is for Canada.