cracks knuckles Time for pedantry.
The term "retro" means "something designed to imitate an older style". For some easy to comprehend examples: Dusk is a retro game, Quake is not. Ion Fury is a retro game, Duke Nukem is not. For some more fuzzy ones: Celeste is a retro game, Mario is not. Doom Eternal is
arguably a retro game in many respects, but classic Doom is not. Hell,
Ground Branch could conceivably be called a retro game hearkening back to the glory days of 1996 polygon tactical shooter
Rainbow Six which itself is not a retro game.
This is an important distinction because it allows us to differentiate between a particular style of gaming, and trends which reference that style. The difficulty is that you can't put just a time cutoff on this kind of thing either. Obviously Rainbow Six isn't a "boomer shooter" despite being essentially contemporary with Quake II. You have to consider mechanics, art style, genre, in addition to timeline.
To be honest I also don't like the distinction between "classic FPS" and "modern FPS" either. It's far too broad, arbitrary and I'd say even derogatory. The evolution of gaming is organic and fuzzy, and our own biases heavily influence a sad good-ole-days tendency to gatekeep some platonic ideal of gaming. Which usually, if we're being honest, boils down to "gaming was good when I got into it, but now it's bad because it changed from what I remember."
