The interview was held on Microsoft Teams. The job posting mentioned English skills being important (many clients are in the UK), it said nothing about Dutch.
The interview with me being in Dutch (I hadn't prepared for the interview in Dutch so I was thrown off), there was one question that I misunderstood which derailed the entire interview.
After that mishap, there was a noticeable change in the tone of the interviewer. The rest of the interview felt like an interrogation. I was questioned about how long I've been in the country and why I wasn't fluent in Dutch yet.
That would have made sense if that job listed Dutch in the job posting. The job posting listed English as the company language, I also have my level of Dutch (B1 and still in afternoon classes) on my CV.
This is the first and only time that I have felt acutely aware of me being an immigrant during an interview. This renews my drive to further improve my Dutch, as to avoid situations like this.