Do you have any source for the claim that the balloon altitude was controlled remotely? I didn't see it mentioned until now.

The Pentagon press secretary said that the balloon was known to have "the ability to maneuver" but didn't offer details. There's some discussion at https://www.scientificamerican.com/article/chinese-spy-ballo...

For what it's worth, this is how the Project Loon balloons worked. It's a proven concept.

It sure is, but the Chinese claim is that this was a lost piece of scientific equipment, out of range for for any active control.

And the Chinese government lies about anything and everything.