Title Block: & character is changed to & character reference in editor upon save

[worldomonation]

Steps to reproduce the behavior

1. Go to My Sites.
2. Click on new post.
3. In the title area, enter text string that includes an ampersand (&).
4. Publish or Update or Save Draft the post.

What I expected to happen

String entered in Step 3 remains unaltered.

What actually happened

String entered in Step 3 is replaced with & character reference.

Context

User scenario #manual-testing

Browser / OS version

OS: macOS Big Sur 11.1 (20C69)
Browser: Firefox Nightly 87.0a1, Safari Version 14.0.2 (16610.3.7.1.9)

Is this specific to the applied theme? Which one?

N/A

Does this happen on simple or atomic sites or both?

Tested on Simple.

Is there any console output or error text?

No

Level of impact (Does it block purchases? Does it affect more than just one site?)

Minor - visual irritant to users.

Screenshot / Video: If applicable, add screenshots to help explain your problem.

https://user-images.githubusercontent.com/6549265/106673388-5f027c00-6566-11eb-8be8-0b6a59976ea5.mov

[worldomonation]

Similar issue, where the HORIZONTAL ELLIPSIS (U+2026) is also replaced with the text u2026 in cover blocks.

[simison]

cc @Automattic/good-mountain seems like an editor integration issue?

[sirreal]

I'm able to reproduce the title issue on Simple sites. Ellipsis in Cover block seems to work fine.

This appears to be Simple-specific.

[noahtallen]

Similar, but only related to titles: WordPress/gutenberg#20490

[simison]

We closed the earlier one in calypso repo #40499

[simison]

@vindl this might be simple site specific, affecting FSE.

[worldomonation]

@simison I tested this again today and was not able to reproduce on either Simple or Atomic.

Would you like this issue to remain open for FSE, or can it be closed?