[Can't manage my playlists and add comments on youtube when Kaspersky is running]

Thank you Flood.

1. Windows 10 Professional v19041.450
2. V21.1.15.500 + Kaspersky Password Manager
3. Free licence
4. 79.0 64bits
5. No
6. Currently yes, but it was the same after a reinitialisation of Firefox (uninstall and reinstall).
7. See attached file privacy.png
8. It seems to have appeared when I installed Kaspersky Security Cloud. The best solution I have found so far is to close KSC.
9. See attached files YT1.jpg to YT4.jpg (my comments are in green)
10. I don’t know what it is.
11. Yes

[Can't manage my playlists and add comments on youtube when Kaspersky is running]

When Kaspersky is running (even with protection disabled),

1. I can’t manage my playlists on youtube: the button to add a video to a playlist doesn’t respond.
2. I can’t post comments under a youtube video: a red “error” displays under the input box.
3. I seem connected to my youtube account, there is my avatar on the upper right (on computer), but the left menu asks me to connect by clicking on a button that leads to an error page from Google: “405. That’s an error. The request method GET is inappropriate for the URL /youtubei/v1/guide. That’s all we know.”

Only occurs on FIREFOX. No problem with other browsers.
How can I make Kaspersky work well with Firefox ?