not in my opinion, no.
i believe this all started with mnet aggressively pushing the boys planet group (which we now know as zerobaseone) as the start of 5th gen, while the show was still airing. so um, no i'm not taking blatant media play as the gospel truth, especially not from mnet!
anyway, generations are retroactively (help i'm having a language crisis is this the right word T.T) decided, so... i guess it's not for us right now to say if this is 5th gen, but for us or even future kpop fans to determine whether 2023 truly marked the beginning of 5th gen or not.