This is not new and they routinely examine bikes for it.

https://en.wikipedia.org/wiki/Mechanical_doping

Article created in 2016.

even before that, eg. WP article from 2015:

https://www.washingtonpost.com/news/early-lead/wp/2015/07/23...

Even before that. 2010 or so they were saying - without evidence - Cancellara used motors in the spring classics.

It's just clickbait to co-incide with the end of the TdF.

Yeah, I think I remember reading about this a long time ago. Either here or on Wired.