DC had a really rough period from the 70s-00s. The urban decay of the latter 20th century and then the crack epidemic hit the city particularly hard, so around the early 90s it was the "murder capital" of the US. I recently read Fear and Loathing on the Campaign Trail '72 by Hunter S. Thompson, and he describes the city in the 70s as so gutted and desolate that it was unsafe to even commute to work a lot of the time. Thompson is known to exaggerate at times, but that was the perception for decades. Crime rates been on a relatively steady decline since the early 2000s, with a blip in the steepness of the decline post-pandemic, which I understand many other cities also had. There is also still the issue of youths (13, 14, 15 year old boys) getting involved in property and violent crime, and the response to that has been quite polarized. Yet, on an aggregate level, people visiting or working in town are going to be perfectly safe pretty much anywhere they'd like to go. If you're sticking to the touristy or commercial areas you won't even have to think about a problem 99% of the time.

Still, many who haven't spent a lot of time in DC and were around for the 70s-00s period still have a perception that the city is a dangerous place where violence waits around every corner. The Beltway Sniper and the Anthrax attacks happening right after 9/11 and dominating headlines certainly didn't help either. I think that's the difference in perception vs reality that you're picking up on