pasteHandler ignores FormattingControls prop

[leorospo]

Describe the bug
Setting the formattingControl prop in a RichTextComponent to ['italic'] will limit the formatting options in said block to only show the italic button.
The problem is that when you copy / paste some text from a word document it will keep the orignal formattimg even if it is not allowed in the component. Moreover because of the lack of the other formatting buttons the user is not able to manually remove the unwanted/unallowed formatting styles.

To reproduce
Steps to reproduce the behavior:

1. Register a Block with a RichText component and formattingControls prop set to italic

            <RichText
                tagName="h4"
                value={text}
                formattingControls={['italic']}
                onChange={(content) => setAttributes({ text: content })}
            />

2. Copy / paste some text containing various combination of bold and italics
3. Try to remove the unallowed bold formatting.

Expected behavior
On paste the unallowed formatting styles are ignored and treated like normal text.

Desktop (please complete the following information):

• OS: Win10
• Browser Firefox Developer Edition

Might reference
Overview: Writing Flow #16280
https://github.com/WordPress/gutenberg/labels/%5BFeature%5D%20Raw%20Handling

[ellatrix]

I'm not sure if this is to be expected or not. The formattingControls props controls the formatting controls. It doesn't disallow certain formatting in the RichText instance. You can still go to the HTML view and add anything you like there. I'm open to limiting paste in this case though.

[leorospo]

The behaviour persist with th allowedFormats prop

[mirka]

Related: #7591

[Mamaduka]

I'm going to close the issue.

Why

• The allowedFormats prop works as designed. The setting controls format options displayed for a RichText instance, not the paste behavior.
• The __unstablePastePlainText can change the latter.