Opera is filing an antitrust complaint against Microsoft in Brazil, alleging it creates an unfair environment for alternate browsers to compete with Edge. The Norway-based company claims Microsoft’s deals to make Edge the exclusive pre-installed browser on Windows machines creates an unfair environment for alternate browsers to compete. Opera also argued that Microsoft uses design tactics and dark patterns to further discourage people from downloading and using rival products. It is asking Brazil’s Administrative Council for Economic Defense (CADE) to pursue remedies against Microsoft.

“Microsoft thwarts browser competition on Windows at every turn. First, browsers like Opera are locked out of important pre-installation opportunities,” Aaron McParlan, general counsel for Opera, said in a statement. “And then Microsoft frustrates users’ ability to download and use alternative browsers.”

This isn’t the first time these two companies have clashed. Opera sued Microsoft in the EU with a similar argument that bundling Internet Explorer was anticompetitive. , it also argued (albeit unsuccessfully) that Microsoft should have gatekeeper designation for the Edge browser under the EU’s Digital Markets Act.