Bold formatting is lost when typing after applying bold

Phenomenon

When applying bold formatting to selected text and then continuing to type, the bold formatting is not maintained for the newly typed characters in Safari.

Reproduction example

1. Create a contenteditable div.
2. Type some text.
3. Select the text and apply bold formatting (Cmd+B or through execCommand).
4. Place the caret at the end of the bold text.
5. Continue typing.

Observed behavior

• In Safari, newly typed characters after the bold text are not bold.
• The formatting state appears to be lost when the caret moves.

Expected behavior

• Newly typed characters should inherit the formatting of the preceding text when the caret is within or immediately after formatted text.