I'm new to this unit so my apologies if this is a very simple question, but I was expecting something like net, 'e', or lu' here, since I thought tlhoD normally has an explicit subject. Is there something I'm missing about how to use verbs in this context, or am I just incorrect about the meaning of tlhoD? Thanks so much as always.
tlhoD is a "be" (or "state" or "adjectival") verb. The subject is the thing that is obscured, filtered, smudged, fuzzy. There is an explicit subject: chal.
If we knew of some verb that meant "to obscure (something)", then I suppose it would work like you are thinking. Instead, if you want to say that someone caused something to be obscured, you have to use tlhoDmoH.