The menu has many options.

The special menu gives the possibility to copy only the style information or the values stripping the style.
The command V gives the style by default.

There's one thing which is interesting.

To reproduce.

1. In A1 Type a word: MOZILLA
2. select the cell A1
3. Copy with keyboard combinations (command + C, Ctrl +C)
4. Go to A2
5. paste
6. We get Mozilla
7. In an app outside of Google Sheets, select and copy a text. (ex: I selected code)
8. Go to A3
9. paste
10. We get code
11. Go to A4
12. paste special -> Values only
13. we get MOZILLA (instead of code). Google kept another memory for the paste special function.

This is probably the issue.

I have contacted them

Sorry, should have realized when first reported.

Ultimately, this relies on programmatic ability to read the clipboard to resolve this case. The Paste special menu is owned by Sheets and would need to trigger a paste in order to get up-to-date clipboard content outside of the application.

In the past, this API has not been available. Is this API now available in FF to programmatically trigger a paste?

I was able to reproduce the issue. Use the right-click command Paste Special-> Values Only, no result is returned:

https://media.giphy.com/media/2s5Jb4MLcvM4OJQLX6/giphy.gif

Tested with:

Browser / Version: Firefox Nightly 101.0a1 (2022-04-07) (64-bit)/ Chrome Version 100.0.4896.75 (Official Build) (64-bit)
Operating System: Windows 10 PRO x64

Notes:

1. Reproducible regardless of the status of ETP.
2. Reproducible on the latest build of Firefox Nightly.
3. Works as expected using Chrome.
4. Possible duplicate: https://bugzilla.mozilla.org/show_bug.cgi?id=1640222

Let's close this as a duplicate of https://bugzilla.mozilla.org/show_bug.cgi?id=1640222