Heading block: Text displayed with smaller font size when enabling any text format (Only on Android)

[fluiddot]

Description

In general, the Heading block displays the text using a bigger font size than the rest of the text blocks. This is the case when typing text on this block, however, if any text format is enabled before typing on Android, it's displayed in a smaller size than expected.

Step-by-step reproduction instructions

1. Open a post/page.
2. Add a Heading block.
3. Type some text.
4. Observe that the text is displayed in bigger font size than the rest of the text blocks.
5. Add another Heading block.
6. Before typing, enable any text format, like for example Bold format.
7. Type some text.
8. Observe that the text is displayed in the regular font size and is smaller than the previous Heading block.

Expected behaviour

Heading blocks should display the text in the same font size, independently of the text formats applied.

Actual behaviour

Heading blocks display text with a smaller size when any text format is enabled before typing.

Screenshots or screen recording (optional)

android-heading-block.mp4

WordPress information

• WordPress version: N/A
• Gutenberg version: N/A
• Are all plugins except Gutenberg deactivated? N/A
• Are you using a default theme (e.g. Twenty Twenty-One)? Twenty Twenty-One

Device information

• Device: Samsung Galaxy S20 FE 5G
• Operating system: Android 11
• WordPress app version: WordPress-Android 19.8.1

[fluiddot]

I still can reproduce this in version 23.9. The wrong font size applied in headings differs depending on the theme, for some are more prominent than others. In any case, it's still happening, and since it's affecting the writing flow I'd advocate keeping the [Priority] High label.