I'm skeptical of that claim as well. I happen to have a roster of product and engineering employees at a FAANG company.
It doesn't include any information about their education but what I can do is pick a selection of the staff level engineers at random and look them up on LinkedIn.
Here's the highest level of education attained by the first 50 I looked at:
7 had a PhD in Computer Science
1 had a PhD in Physics
1 PhD in Electrical Engineering
12 had a master's degree in Computer Science
1 had a master's degree in Computer Engineering
1 had a master's degree in Information Management
13 had a bachelor's degree in Computer Science
1 had a bachelor's degree in Electrical Engineering
1 had a bachelor's degree in Information Technology
6 did not list any educational experience
6 I could not find on LinkedIn
I did not see any that mentioned a coding bootcamp explicitly.