From what I can see from screenshots it seems like you’re including some Google’s libraries as JARs, which is not supported (or correct thing to do).
For example, Vungle’s plugin used to include support-annotations-27.1.1.jar, support-compat-27.1.1.jar and support-core-utils-27.1.1.jar and other files from shared libraries. Deleting those files and using shared dependency plugins helped similar issue.
Also, there is new dependency, which isn’t documented yet: “shared.google.play.services.ads.identifier”, because “shared.google.play.services.ads” after update to 17+ requires admob identifier.
It is really hard to tell what is wrong in your private plugin setup without seeing it.