I don't think "Clear Recent History" honors cookie exceptions.

A multi-step workaround would be to use the "Manage Data" dialog:

(1) Open the Settings page and click over to the Privacy & Security panel

(2) In the Cookies and Site Data section, click the Manage Data button

(3) Click the Site heading to alphabetize the list, and scroll down to the site you want to preserve. Click the site above it and press Ctrl+Shift+Home to select all of the sites above that. Then click Remove Selected.

(4) Click the site below the site you want to preserve and press Ctrl+Shift+End to select all of the sites below that. Then click Remove Selected.

(5) Assuming that worked and you just see the site you want to keep on the list, you can Save Changes. If somehow you removed the site you don't want to remove, click Cancel and start with step #2 again.

Hello and thank you for the suggestion.

I did some testing following your directions:

"Save changes" actually applies the choices made you suggested in steps 2 and 4 and has no effect to create an exception to history deletion.

My goal was to avoid having to authenticate on web.whatsapp.com using the QR code every time I delete the history, since that site do not use login credentials that you can save on FF password manager.

I then found out that web.whatsapp.com does not use cookies for authentication and I was able to get what I wanted by deleting the history as mentioned in my first post but additionally unchecking the "Offline website data" check box.

I then found out that web.whatsapp.com does not use cookies for authentication and I was able to get what I wanted by deleting the history as mentioned in my first post but additionally unchecking the "Offline website data" check box.

Aha, that was a good discovery. Firefox considers cookies and offline website data to be two peas in a pod because they can both be used to store tracking information. However, as you discovered, you can manage them separately with a little bit of difficulty.