So you are saying that behind visible list of apps that are either "optimized" or excluded there is another hidden list where app that is "optimized" could be actually excluded? Ok, that can be a working hypothesis. Why is Skype not excluded the same way then? Or Slack? Millions use them and MS surely has money to promote their app this way. Why Whatsapp is not excluded? It's owned by FB.
Though they were moving away from that model to a model where apps alive for more than a certain time interval in background were killed. So apps which you use the most heavily are more likely to be penalized.
Interesting information. I'm not doubting you here but want to clarify one thing, to understand. After you contacted Oneplus and were added to whitelist, do you still see that your app is showing as "optimized" in the settings but app behavior changed and it is no longer killed in background? And that same is applicable to other major software?
I don't know why it's not there, I'm not an exec in those companies. I know for sure that OnePlus, Huawei and Xiaomi have such whitelists. Other OEMs might have them as well.
This isn't climate change debate, it's easy to check.