Why YSK: It appears several Lemmy Instances are flagged as suspicious and at least 1 instance intentionally using the name of ransomware. A couple of the big enterprise monitoring suites (Fortiguard, ZScaler) will flag your account and may end up with you being pulled into an office for an explanation, or worse.
TL;DR: Keep browsing to your local instance at work for now.
The company firewall very likely is using a "content filtering" function which for Sonicwall, for example, is a subscription service where the admin can select any number of "categories" of content to block. I found lemmy.world was being blocked because Sonicwall had that domain categorized as "gaming" which was disallowed. I reported the error to Sonicwall that it should be "social media" but haven't heard back (it takes a while) but some companies might block that category also. In short, it might not be blocked because of any positive action by your company but instead by accident because whoever first classified the site didn't understand what it was.