Neither, because it's too ambiguous with no clear answers.
The only reason we have numbered generations in the first place is because of A) the fact that most home consoles typically released with similar capabilities and within a relatively narrow time window that all competed directly with each other, and B) a consensus on organizing systems by cohort arose on Wikipedia years ago and it just kinda stuck in gaming discourse.
This system worked fine for home consoles of note released after the Crash of '83. We had the 8-bit NES & Master System in 1983-85, then the 16-bit Genesis & SNES in 1989-91, then the 32-/64-bit PS1, N64, & Saturn in 1995-96, and so on. It still works fine with Xbox & PlayStation. But it never really worked well with older consoles. It's still debated on whether pre-Crash cartridge-based consoles are one or two generations, and there's no clear answer. Handhelds don't always fit neatly into these categories, either. For example, was the Game Boy both a fourth- and fifth-gen system since it lasted the entirety of the 90s, or was there just no Gen 5 handheld? Was the Color its own system (Nintendo doesn't think so, but some others do), and if so was it fifth-gen because it followed the original or sixth-gen because it launched just a few weeks before the Dreamcast did in Japan?
Now we have the Switch, which launched almost right smack in the middle of an ongoing generation. It was released about 39 months after the PS4 & XBO and 45 months before the PS5 & XBO, so closer to the start of the former than the latter. But because of its unusually long life cycle (by Nintendo standards), as of this past summer it's now spent more time competing directly against the PS5 & XBS. So, which metric do we use? Which systems it launched closest to? Which it spent more time competing with? How does one determine which is the better standard besides arbitrary personal preference? The NPD Group considered it "current generation" when it was going up against the PS4 & XBO, and they still consider it current-gen after over four years of competing with the PS5 & XBS. Looks like they consider a "current generation" console to be one within its primary life cycle, so the Switch will simply become "last-gen" once the Switch 2 comes out.
If it's this confusing then why bother assigning either Switch to a numbered generation? The only reason to bother is to be part of another pointless online pissing contest over electronic toys. "Mine was the first next-gen console!" "Nuh-uh! It was the last current-gen console so :p!" Yeah, I was part of those arguments myself, but quite frankly I don't care anymore. Call it whatever you want. Just don't be a dick about it.
Also, I imagine if Xbox starts to deviate as well and no longer sync up hardware releases to PlayStation or even just stops having ordinary "generations" altogether, that's going to open up a new can of worms in nerd debates online. At that point, we might as well just stop arguing about "generations" altogether. It was useful shorthand for like 30+ years, but that could be coming to an end. There has been and will likely continue to be many examples where the answer is so unclear that if you asked twenty gamers you'd probably get thirty different answers. No, that wasn't a typo.
Visit http://shadowofthevoid.wordpress.com
Art by Hunter B
In accordance to the VGC forum rules, §8.5, I hereby exercise my right to demand to be left alone regarding the subject of the effects of the pandemic on video game sales (i.e., "COVID bump").