Anyone else having issues with the mobile app automatically adding tax to every line item?

Let's perform troubleshooting steps to fix the issue, User. 

We can refresh your mobile app's data to ensure that the information from the regular browser is syncing with the mobile app. At the same time, it resets the application. Please know that the steps may differ depending on the operating system that you're using. 

For Andriod:

1. From the More Options ⋮, select Settings.
2. Tick Refresh Data, then choose Yes.

For IOS:

1. From the Menu ☰, select Help & Feedback.
2. Click Refresh Data, and then select Refresh.

You can also do it in your device settings. Here's how:

For Andriod:

1. Go to your device's Settings, and select Apps (varies by device).
2. Choose the QuickBooks app from the list, and then pick Storage.
3. Hit clear data.

For IOS:

1. Go to your device's Settings, and select Setting General iPhone Storage.
2. Choose an app that's taking up a lot of space.
3. To free up the storage without deleting the documents and data for the app, select the Offload App.
    

However, if the issue persists, try uninstalling and reinstalling the app to resolve unexpected behavior on mobile devices, and ensure updated security settings are downloaded. 

Furthermore, learn how to filter specific reports to make sure you'll get the right data for your business needs. Read this article for more details: Customize Reports In QuickBooks Online.

Get back to us here if you have other questions or concerns. I'm always here to help