Indie is really such a vague term that encompasses such a massive array of genres now, it's really just a sound, a style, and more refers to music (of any sort) that a certain type of people listen to. I'd much prefer music being labelled as what it is. Like you say: synthpop; electropop; chillwave; no wave; shoegaze; dream pop; post punk; and so on. It was a similar thing with alternative music in the 90s, although nowhere near as pervasive.

to Avril Lavigne and Good Charlotte. Blink-182, Sum-41, Jimmy Eat World, Fall Out Boy, Paramore. And so many other pop punk bands for that matter. So bad.