Oh, as a noob dev my team was using a dropdown library for our filters in the website. The code was messed up cause they kept changing the design halfway through dev and after releases and then finally after some releases, the client wanted multilevel options as a new requirement.
So I scrapped the whole thing and made my own multilevel dropdown component (there were no decent libraries then) and we used that from then on. It has many issues now that I look back (who cares about keyboard interaction right?). But that is a refactor for another day.