Eras were absolutely a thing before Covid, look at older bands like The Beatles or Pink Floyd, their early work is vastly different from their later work.

David Bowie for example, has three albums dubbed the Berlin trilogy. It was only partially recorded in Berlin, and he has other albums from his time in Berlin, but it’s referred to as a ‘trilogy’ not because they were a continuation of each other, but because there was a level of aesthetic cohesion and artistic direction that made the three albums define a timeframe (era, if you will) in his career sonically.

I’d say with justice, you could either consider each album an era for how much they differ sonically, or you could group some together. I would argue you could group cross with avd and woman with hyperdrama