Create a new build phase, run script, make sure to move it to the top, you may name it something like "Copy Google-Services plist", and use the following content:
PATH_TO_CONFIG=$SRCROOT/Configs/GoogleService-Info-$CURRENT_FLAVOR.plist
# https://github.com/firebase/firebase-ios-sdk/issues/11400#issuecomment-1609413066
GSPLIST_FOLDER="$BUILT_PRODUCTS_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH/"
mkdir -p "$GSPLIST_FOLDER"
cp $PATH_TO_CONFIG "$GSPLIST_FOLDER/GoogleService-Info.plist"