Facebook has been stagnant for a while, as they focused on pushing advertising and monetising users. It's not just "uncool", it's broken what made it good in the first place. I left Facebook a few years ago due to it's enshittification, and it's very very different to what it was right back at launch. It's a very similar issue to Reddit's but just manifesting in a different way.
Meta bought Instagram and Whatsapp to stay ahead of it's competition, particularly with younger users when it comes to Instagram. It's increasingly pushing ads on Instragram and trying to monetise users, and at the moment trying to monetise Whatsapp by getting businesses to pay for access via new tools. They've already changed terms of services on Whatsapp to the benefit of businesses and Meta, and are trying to merge it in with Facebook and Instagram messaging. On all platforms it is harvesting and selling user data.
Meta's revenues fell for the first time in 2022, and profits are also down, plus the "metaverse" is not succeeding despite heavy investment. Expect "enshittification" to accelerate as ultimately Meta cares about it's share price more than anything else, and shareholders in the tech space expect year on year growth. Meta's pivot to the Metaverse is because the company knows there is not much growth left in it's core social media products, and also a lot of competition it's struggling to beat (TikTok for example).
Meta is treading water at best, and it already monetises it's users and disrespects their privacy and data in ways that people wouldn't tolerate if they understood what is going on. I honestly wouldn't hold Meta up as a company that Reddit should look to for good PR.
Reddit Goes Nuclear, Removes Moderators of Subreddits That Continued To Protest (www.pcmag.com)