In a few weeks, 1% of creators already using YouTube Studio will no longer see the ‘back to Classic’ button – you’ll be notified 1st & can still access Classic features you need! This won’t apply to everyone else until early next year. More info → https://yt.be/help/a7mG
I would be genuinely interested to hear the rationale behind this change, as the rest of the community and I can't see any good reason for it. At the very least, please give us an explanation. Have some transparency.