I tried the methods below, and the issue was resolved on my end. First, I updated the version and build number in the pubspec.yaml file. The old version was 1.0.1+180, and I changed it to 1.0.2+181. Then, I added the ITSAppUsesNonExemptEncryption key to the Info.plist file and set its value to false.
Example:
Info.plist:
ITSAppUsesNonExemptEncryption
Topic:
App Store Distribution & Marketing
SubTopic:
TestFlight
Tags: