I was afraid of that as well given the wording but, no, it's nothing to do with third parties at all. Just when you log into a new device, you confirm it on your old device so it knows it can transfer encryption keys for old messages to the new device

This has been in Element/Matrix since forever and I found it the easiest verification mechanism of all the encrypted messengers I've tried. I'm not surprised they're making this part of the standard process, but the wording in 2025 is... unfortunate. Or perhaps that adjective should be applied to the rest of the world since it's not the Matrix Foundation which changed. For the reader to decide ^^