Why rival browsers want EU to take action against Microsoft Edge

Several web browser developers have urged the regulators in the European Union (EU) to take action against Microsoft, alleging that the company is unfairly promoting its Edge browser on Windows at the expense of competitors.
In a letter to the European Commission, Vivaldi, Waterfox, Wavebox and the Open Web Advocacy group argue that Microsoft is exploiting its dominance in the PC market to give Edge an unfair advantage, as per news agency Reuters.
They point to Edge being the default browser on Windows and allege that Microsoft uses misleading pop-up messages to discourage users from switching to other browsers.

These companies support a legal challenge by Opera, which argues that Edge should be subject to the EU's Digital Markets Act (DMA), which aims to prevent large online platforms from abusing their market power and ensure fair competition.
“It is paramount that the Commission reconsiders its position,” they said in a letter.
“No platform independent browser can aspire to match Edge's unparalleled distribution advantage on Windows. Edge is, moreover, the most important gateway for consumers to download an independent browser on Windows PCs,” the group added.
They claim that since Edge comes pre-installed on Windows, it gives it an advantage as it becomes the primary way for users to download other browsers. They also said that Microsoft misrepresents the features of competing browsers in its pop-up messages.

In a February decision, the European Commission exempted Edge from the DMA, stating that it didn't consider it a dominant player, hence it cannot be considered as a gatekeeper. Notably, Edge's global market share is about 5% while market leader Google's Chrome is 66%, as per StatCounter.