I've noticed that sometimes adapters can take a very long time to initialize via MobileAds.initialize.
For example, for the ad source of Vungle/Liftoff, I've noticed that sometimes it takes it 30 seconds (!) to initialize, so I get no ads for more than 30 seconds since the app started, which is terrible. That's compared to less than 1-2 seconds of all other ad sources.
Such a thing reduces revenue because sometimes users enter the app for a short time.
Please add some protection against this behavior, such as:
1. Have some QA testing on each of the adapters, each time there is a new version of it.
2. Have some timeout for initialization, and offer a customized one too. When the timeout is reached, just let us load ads from whatever we have now, not waiting for the problematic ad-sources to initialize.
3. Let us have the callback be a bit different, so that we could notice such a behavior ourselves, and maybe go to a different version of the ad-source, or decide something else. We could also have some information about why it took so long.
4. Each time an adapter misbehaves this way, contact the ad-source company about it, to try to fix it together.