Block inserter menu jumps when interacted with on small screens

[tellthemachines]

Describe the bug

When opening the block inserter menu on small screens (< 782px), it occupies the whole screen. However, trying to interact with it in by focusing the search field or opening a section causes it to be pushed to the location of the clicked inserter .

I also checked on the xcode simulator (iphone 11) and the menu is opening directly from the inserter, instead of taking up the whole screen.

To reproduce
Steps to reproduce the behavior:

1. Using a phone or tablet in portrait mode, click the block inserter on a post or page.
2. Click on the search field.
3. Verify inserter menu jumps to bottom of page

Expected behavior

Expect menu to expand to fill the screen on open and stay in place when interacted with.

Screenshots

Android (Samsung Galaxy S5):

iOS simulator (iphone 11):

Smartphone (please complete the following information):

• Device: All devices

Additional context
Latest master, and plugin version 7.2. Doesn't happen in core version.