Describe the bug
While testing the writing flow, specifically the test case "Splitting and merging - TC002 - Merge after selection", I spotted that selecting and deleting the first word, the block stops being rendered as a header, instead it looks like a regular paragraph.

I managed to reproduce it also by selecting and deleting the first letter of the content.

To Reproduce
Steps to reproduce the behavior:

1. Go to a post/page
2. Add a Heading block
3. Write some text
4. Select the first word (it should include the first letter of the content)
5. Tap Backspace key for deleting it
6. Observe that the block stops being rendered as a header instead it's rendered as a regular paragraph

NOTE: This issue can only be reproduced using the Samsung Keyboard (factory default). With the Gboard it works as expected.

Expected behavior
Heading block should be always rendered as a header (bigger font size and spacing).

Screenshots

Smartphone (please complete the following information):

• Device: Samsung Galaxy S20 FE 5G
• OS: Android 10
• Version: 16.5 and Pre Alpha - Build 94309