Even my 'z' shortcut doesn't work to gain the focus mode
Focus-Mode is gone
for me it still wont show..
i dont know why, haha and its getting frustrating lol
i can lower the browser zoom all the way down, and it still wont show.
im using a single monitor (just my laptop)
and im using chrome
nothing seems to get it to work, and show, any ideas anyone??

I had the same problem, solved by activating "always use focus mode" in the live chess settings. That strangely doesn't activate the focus mode ..... but the button is back and operational.
(firefox, dual screen, and zoom doesn't change anything on my config)

The same problem for me. They should really fix this. For now I am just playing on lichess instead.
It must be a browser issue. What browser are you using?
It's still there for me using the Chrome browser.
I use the latest version of Firefox (121.0). When I apply Focus Mode, I can still see my opponents' usernames and nationalities (their ratings remain hidden until the games end, though).

It appears that the functionality is not operational on the computer I am currently using to compose this message. Interestingly, my other computers, which run macOS, function without any issues. However, the device I am presently using, operating on ChromeOS, experiences difficulties. Hence, I recommend that Chess.com investigates this matter, as it seems to be specific to the ChromeOS platform.
"it might be your dual monitor.." for the desktop yes.. but still no luck on the laptop..