PayPal is in the crosshairs of German regulators over concerns that it used its market dominance to stifle competition.

PayPal is a popular online payment processor and money transfer platform. In many countries, it’s the de facto standard payment method for buying and purchasing online.

According to Reuters, however, German regulators are concerned the company may have abused that dominance in an effort to ward off competition. In particular, the antitrust regulator raised concerns over clauses in PayPal’s agreement that say sellers cannot show a preference for other payment methods, or make it easier for customers to use them.

“These clauses could restrict competition and constitute a violation of the prohibition of abuse,” said chief Andreas Mundt.

“We will now examine what market power PayPal has and to what extent online merchants are dependent on offering PayPal as a payment method.”