My iPhone charging case says it’s charging my phone but my phone just keeps on losing battery and the charging case doesn’t lose battery.

I have the newest charging case for iPhone 7. My iPhone 7 is currently running iOS 12.1. I’ve restarted my phone, done multiple forced restarts, turned it off for a while, etc. The case also didn’t charge my phone when it ran iOS 12.0 nor my friends iPhone 7 also running 12.1. At this point I think it’s either the case being faulty or a glitch in iOS.