Credit card companies will label a business or merchant as high-risk based on the industry the merchant is involved with and other factors, such as age of the business, number of chargebacks incurred and credit history.* High-risk merchants can still accept credit card payments, but banks might charge a higher processing rate or ask for a reserve on credit card processing. Some merchants might always be classified as high risk simply because of their industry or if they frequently sell to customers in foreign countries, etc. However, some businesses can be reclassified as low-risk after proving they can meet certain criteria set by the bank.*
*https://mypaymentsavvy.com/industry-payment-processing-solutions/high-risk-merchant-account/
*https://www.ballisticmerchantservices.com/articles/what-is-a-high-risk-merchant-account.php