I have to say that what you are experiencing is a bit odd and I say that because I have done that tutorial too and it works fine for me. My Podfile looks like this:
# Uncomment the next line to define a global platform for your project
# platform :ios, '9.0'
target 'FirebaseDemo' do
# Comment the next line if you don't want to use dynamic frameworks
# Pods for FirebaseDemo
As you can see there is only one pod definition and that’s all that Micah used in his tutorial as well so I think you should be sticking to that approach.
I just checked my project and did a fresh build after a pod update just to see what changes have been made to pods since I last used the project. When the pod update completed I opened the project, cleaned it (Shift + Command + K) and waited for it to re-index the files then performed a build. There were a bunch of warnings about iOS deployment targets and some other obscure warnings.
Edited the Podfile and uncommented the platform directive to be
platform :ios '14.0' then performed a pod update. Re-opened the project in Xcode and performed a build. Xcode recommended performing a series of updates to the build target settings for some of the Firebase frameworks which I did and then performed another Build. The remaining warnings are having no material affect on the project and the last query I had defined ran fine.
Other than the comments above I have no insight into why your version of the project is not playing the game.
OK I see you have now solved it. Good news.