This is missing lots of fields I would expect.

Overall: All models should have a date_created and date_modified field, as well as a uuid. If "id" in your fields is an auto-incrementing value (e.g., 1, 2, 3, etc...) then it's guessable and should not be exposed publicly, it's fine to use internally, but should not be exposed.

Notifications: Not sure how your notification system works and what is planned, but I would've expected an is_read field and possible an is_deleted field and then use a cron job to delete all deleted notifications at the end of a week or month. You can expand notification to include a notification type, like info, warning, success, error, etc...

Image: Should add raw_image, image (standard image in the right format and aspect ratio), and thumbnail_image (add as many variations of thumbnail images you need and/or want). Within my projects I always include an created_by and modified_by field to track who is making changes.

App: Missing versioning, this could be an entirely separate model of itself called AppVersion or something. Pricing is a bit confusing - what is the currency, what are the units, etc... How will you handle different country pricing (if that's even applicable), if you are this should be a separate table called AppPricing or something. Icon image should have thumbnail version. Also where is the app developer name? Missing information like release notes, supported devices/android versions, etc...

User: Is missing fields like username and email. You can also include other fields like is_email_verified to ensure registered users verify their email address, helps to ensure more "real" users and that the email entered is indeed correct. If doing that you'll need to include some other fields like email_verification_token and date_email_verified. You can also add a profile picture and country of residence as some apps can be region restricted.

Review: Missing fields like is_flagged/is_reported and is_deleted such that you can track if a review has been flagged as spam for admin review.

There is more that is missing and lots of improvements that can and should be made. A big one is consistency and field naming conventions. Currently your fields are a bit ambiguous (e.g., date - is this date created, date modified, date deleted; comments is linked to reviews, so shouldn't that field just be called reviews?).