I am always asked what I think of when someone lists "ex" in their headline to mention where they use to work.
This is usually used in reference to working for F500 companies and most exclusively within FAANG where there is some sort of strange obsession and perception of elitism that only engineers seem to adhere to. (Sorry guys, you know I love you).
The truth is, of COURSE, there is value to listing names of companies that ignite familiarity bias but saying "ex-Apple" on your headline can work against you.
I have worked with many managers who when reviewing profiles and seeing "Ex-Google," "Ex-Chase," or "Ex-Lexus" say either "I wonder what happened to them and why they were let go" or "Is the best part about this person where they used to work?"
There is a VERY easy solution for this that gives you the benefit of the name brand company, but without potentially pulling those triggers, and that is to use them in the industry section.
Using these techniques allows you to continue to benefit from the familiarity activation of household brand names, but without attaching a potential negative stigma to it.