Description

If you add multiple sub menu items and then hit backspace at the beginning of the second item, it merges with the first.

Step-by-step reproduction instructions

1. Add a navigation block
2. Start new.
3. Add a Link Block.
4. Use the toolbar option to add a sub menu item under the link block you just created.
5. Do this once more.
6. Go to the very start of the second sub menu item you created and hit the backspace.
7. Find that the sub menu items merge together.

Expected behaviour

I expect the items to stay separate.

Actual behaviour

They merged :)

Screenshots or screen recording (optional)

WordPress information

• WordPress version: 5.7
• Gutenberg version: 10.2.1
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? TT1 Blocks

Device information

• Device: Desktop
• Operating system: MacOS
• Browser: Chrome 88