If they did go through that process, I wonder if there's a written guide somewhere, on how to go about it.
Based on my experience working with and for a few startups, it's likely that many of them did not. I've been asked by CEOs to not remove Company X logo even though there was no relationship beyond a customer account which used a Company X email address.
However, as several folks in this thread have noted, the process of working with customers' marketing departments is an opportunity to build relationships. Some won't let you, and that's fine. Companies like Apple often don't even let vendors who are core to their business use their name.
At best, this seems like a pretty easy way to convert them into a former customer.
The other wheeze for startups with few or no customers who want some recognisable badges on their home page is padding the "we work with" section with logos of companies where they use that company's product rather than vice versa...
Well, those badge-worthy companies can preemptively ban your product as well as future business development/co-marketing opportunities. If you never see yourself having an actual relationship of any kind with those companies, and your ethical bar is that low, then you may decide it's worth it.
Certainly, many crypto companies are practicing this form of wishful thinking right now.
https://www.theverge.com/2022/7/29/23284330/helium-crypto-me...