In the sense that its not 6e, yes, but the changes ARE significant to many things, its not just just Tasha's + Tweeks, I mean not every massive change took, but enough big & small changes to various things that most of the classes/species play different.
I think folks are down playing how transformative it is, yes its compatible with most of the stuff in past books, especually Races, Linages, and Species as well as subclasses and adventures, but capablitie and complexity is vastly different, even given that most of the biggest changes got dumped.
what big changes exactly?
there are just little tweaks.
Mastery?
Yeah, they could not admit that Battle maneuvers should have been core fighter if not core for all non full-spellcasters, so we got this super-light version of it.
paladin smite got nerfed and monk got buffed, that can be done by anyone with 10 min worth of house ruling.
1st level feat for everyone? Yeah, just put in most popular house rule for 5E as default. They really put the brain trust to work on that one.
we got basically only one draft of new version of feats, so my hopes are that aspect will get balanced and improved in final print.
most good(big) changes got rolled back because of "muh compatibilitah" with past books, which will be thrown out as soon as "Xanatar 2" or "Tasha 2" hits the shelves in 2025/2026.
universal sub-classes progression? removed.
sub-classes for multiple classes? removed.
cantrips for paladins and rangers? removed. let them spend fighting style instead. We cant have that by default. It might seem as that not giving them in 2014 was a mistake.
all subclasses moved to 3rd level as new players are too stupid according to devs? checked.
inflating ability scores? checked.
instead of thinking of new cool feats, lets just remove a feat slot from characters and force them to take 22 in their primary as that is mechanically best option to get.