I guess if you make an emotional connection to something, then it's deep in a subjective way.
I personally thought Links Awakening was deep which might come off as silly to other people. It's a gameboy game for kids. Some people find Bluey deep, but I don't really see it. I guess some people see something there that they connect with.
On the flipside, I have seen cooperate stuff attempt to be "deep" and it can come of as hallow and gimmicky. Big budget DC movie made by WB stating "We live in a society." or the Barbie movie (also WB) trying to state that we fix Barbie by making her more "real". It comes off as pandering.
There is also the stuff that is sort of on the fence. People who like Rick and Morty are going to find it deep. Those who don't like it, are going to find it annoying and just reddit "I'm 14 and this is deep" BS. More or less, if you don't like something, you aren't going to find it deep.