[AC Question]

I've been getting ads in default built in apps, such as the camera, photo gallery, and messenger. Is this normal? I seriously doubt that they would do this.

[Marxbro]

As far as I know there shouldn't be any ads appearing in the apps you have mentioned. It is possible that you may have accidentally added some malware or adware to your phone. I suggest that you try a program like Malwarebytes which is free from the Google Play Store. You can also try and protect your phone from future problems by using an antivirus app. I use AVG Antivirus myself but you can choose whatever you like. Good luck with the problem, hopefully Malwarebytes can do the trick.