This button doesn't have a specific access key (keyboard shortcut), so you need a workaround. You can set focus to the location bar (e.g. F6 or Ctrl + L) and then press Tab to set focus a button on the Navigation Toolbar. You can press the first letter of the tooltip you see when you hover a toolbar button. That way you can jump to this button. The Text Encoding button has a "Show text encoding options" tooltip, so you can press the 's' to jump to this button (not really intuitive). If there are more buttons that have a tooltip that starts with 's' then you need to press the 's' key more than once or move the button to a position at the start of the list. Press Space or Enter to activate the selected toolbar button.

Unfortunately, with Ctrl L, when focused, tab is skipping this option (in particulat page that I open), it goes to refresh and than goes to the page. F6 is something else. Only on blank page it goes directly to page encoding option, because there are no others (refresh, etc).

Can you make that we define keyboard shortcuts as needed?

You should stream that, computers work, merely when we look at them. This is to much complicated.

Look what I was thinking, that is skips the encoding button, on attached print screens

Did you try to press the 's' key like I posted above to select this specific Text Encoding button? Note that this also works if the three-dot Page Action button is selected.

You use the Tab key to select a container. When you are in a container then you can use the cursor Left/Up and cursor Right/Down keys to navigate within this container.

It could work after one tab and S. Thank you, but it should be prepared that we make our only shortcuts.

Hi

While the toolbar button does not have a keyboard shortcut, on Windows and Linux, the entry point in the View menu does. Press alt-v to show the view menu and, once the menu is open, press c. That's enough starting in Firefox 91. In earlier versions, then press u. (The keys may differ for non-U.S. English locales.)