The U.S. Justice Department (DOJ) antitrust investigation against Google (GOOGL  )regarding the company's practice of bundling Google Maps with other Google offerings is heating up again. The investigation was opened in 2020 but was "quiet" until investigators began making inquiries again in the past few months.

In 2020, a congressional antitrust report about Big Tech revealed that Google "aggressively" restricts app developers from using Google Map rivals if their apps rely on any other Google service. The report states that developers are forced "to choose whether they will use all of Google's mapping services or none of them."

This restriction for developers makes up one of the key components of the DOJ's investigation into Alphabet Inc, Google's parent company.

The second branch of the investigation is looking into restrictions on the use of non-Google services alongside Google products for vehicle infotainment screens. Google's Automative Services package bundles the Play Store, Google Assistant, Maps, and other Google products, stopping car companies from seeking rival alternatives for any of those services.

"We always cooperate with regulators and are glad to answer any questions they may have about our business," a spokesperson for the company told reporters.

Google says that its auto bundling and developer restrictions ensure users get the best experience possible. It added that these policies do have some exceptions.

According to a report from Reuters, at least two developers have received violation notices for mixing Google's services with rival map providers. The developers told Reuters that the alternatives were either less expensive or more detailed than Maps. Along with these violation notices, developers using rival maps may also be more restricted from collecting user data.

Data is a key aspect of Google's efforts to dominate the digital map market. The ubiquity of Google Maps gives the company access to mountains of data on user behavior, helping them to crush competitors.

At this time, it is unknown whether or not the DOJ will recommend an antitrust suit against Alphabet. While bundling has frequently been the cause of these sorts of suits, bundling products isn't always against the law.

However, Google is already facing one antitrust lawsuit filed in 2020 regarding how the company came to control the search and online advertising market. That case is scheduled to go to trial in September next year.

Alongside these investigations, a high number of merger requests have also recently been filed with the DOJ, holding up progress.