A new report shows Facebook has an uphill battle ahead as it tries to combat claims of anti-conservative bias on the popular social media platform.

A review of Facebook released Tuesday by Arizona Republican Senator Jon Kyl and a team from the law firm Covington & Burling led Facebook to agree to more transparency of how it ranks its “News Feed” content and moderates its community, according to CNBC.

One way Facebook showed its compliance is by changing its “sensational” advertising policy so as not to block anti-abortion ads that show medical tubing coming out of human bodies. But the report shows there is still plenty of work to be done in the future.

“Facebook has recognized the importance of our assessment and has taken some steps to address the concerns we uncovered. But there is still significant work to be done to satisfy the concerns we heard from conservatives,” the report said.

While interviewing more than 130 conservative groups, lawmakers and individuals, Kyl and his team found categories of concern within Facebook, including advertising policies and enforcement, content distribution and algorithms.

Algorithms were a chief concern because some of the interviewees feared the equations that decide what users see prioritize “in ways that suppress their viewpoints,” according to the report. Facebook changed its algorithm in 2018 to favor content from users’ family and friends, but some argue the algorithms may be filtering conservative news content, too.

Facebook’s hate speech policy came under fire in the report as well, as some conservatives interviewed argued the policy was highly subjective. Some pointed to the social media giant’s reliance on “left-leaning organizations to identify hate groups” as part of the problem.

Ultimately, many of the interviewees pointed to Facebook employees’ natural biases as the root of the entire social media bias issue.

This is only the latest in a string of allegations facing Facebook and other big social media and technology companies like Google and Twitter. Executives from each have faced lawmakers in defense of their moderation practices in recent months. Sen. Josh Hawley, R-Mo., introduced legislation that would voluntarily audit a platforms’ policies for “political neutrality” in exchange for legal protections, according to CNBC.