Bugzilla

**Notes**
- Does not reproduce in Chrome. Please see the attached video for more details.

**Found in**
* Nightly 110.0a1;

**Affected versions**
* Nightly 110.0a1;
* Firefox 109.0b8;
* Firefox 108.0.1; 

**Tested platforms**
- macOS 12;
- Windows 10;
- Ubuntu 22; 

**Affected platforms**
- macOS 12;
- Windows 10;
- Ubuntu 22; 

**Unaffected platforms**
- N/A; 

**Steps to reproduce**
1. Launch Firefox and go to https://mail.yahoo.com or https://mail.google.com.
2. Log in with a valid account.
3. Click on "Compose" to open up a new e-mail window. 
4. Write 2 phrases, each with different text size, color, etc. 
5. Merge the phrases on the same row by hitting Backspace.
6. Type something between the two phrases.

**Expected result**
* Formatting should be taken from the left text block.

**Actual result**
* Formatting is taken from the right text block.

**Regression range**
* Will look for one as soon as possible.

**Notes**
- Does not reproduce in Chrome. Please see the attached video for more details.
- This reproduces with `editor.join_split_direction.compatible_with_the_other_browsers` with both `true` and `false` values. 

**Found in**
* Nightly 110.0a1;

**Affected versions**
* Nightly 110.0a1;
* Firefox 109.0b8;
* Firefox 108.0.1; 

**Tested platforms**
- macOS 12;
- Windows 10;
- Ubuntu 22; 

**Affected platforms**
- macOS 12;
- Windows 10;
- Ubuntu 22; 

**Unaffected platforms**
- N/A; 

**Steps to reproduce**
1. Launch Firefox and go to https://mail.yahoo.com or https://mail.google.com.
2. Log in with a valid account.
3. Click on "Compose" to open up a new e-mail window. 
4. Write 2 phrases, each with different text size, color, etc. 
5. Merge the phrases on the same row by hitting Backspace.
6. Type something between the two phrases.

**Expected result**
* Formatting should be taken from the left text block.

**Actual result**
* Formatting is taken from the right text block.

**Regression range**
* Will look for one as soon as possible.