If you go to the page for the spell True Polymorph, at least on mobile, the language still says "permanent". It was updated and should say "until dispelled". It is correct if you look at it in the players handbook, just not if you search the spell and open the standalone page.

I'm looking at the 2021 Player's Handbook errata document and I'm not seeing any mention of changes to the language from 'permanent' to 'until dispelled'

True Polymorph (p. 283). This spell can’t affect a target that has 0 hit points.
In the second sentence, “the creature into an object” is now “the creature into a nonmagical object.”
In the “Creature into Object” subsection (p. 284), the following text is appended to the first sentence: “, as long as the object’s size is no larger than the creature’s size.”

Comparing the listing to the Player's Handbook (and Basic Rules), all three appear to use the word 'permanent', assuming you're referring to the last paragraph of 'Object into Creature'

If the spell becomes permanent, you no longer control the creature. It might remain friendly to you, depending on how you have treated it.

If you can provide more info on where you're sourcing the updated information, that'd be great.

It is how it reads on the dndbeyond website here. End of the 1st paragraph.

https://www.dndbeyond.com/sources/phb/spell-descriptions-tz#TruePolymorph

" If you concentrate on this spell for the full duration, the spell lasts until it is dispelled."

Crawford references the update here.

https://twitter.com/jeremyecrawford/status/723569059640401921?lang=en

It is just how it is supposed to read.