This is a serious security concern!!!!! Who came up with this idea. Never ever should a stored password be shown in text to a user even if they have the password for their device.

Then change the Wi-Fi password.

See -> Recommended settings for Wi-Fi routers and access points

Recommended settings for Wi-Fi routers and access points - Apple Support

The Wi-Fi network name, or SSID (service set identifier), is the name your network.

And every Wi-Fi network name has a Password.

So sign in in the router and check.

Many routers have a 'guest' password, check if your router has that too.

You can change that guest password as often as you like.

I know it's a privacy issue. But usually when the password is shown it's a forget or remember sort of situation. It's shown because you may accidentally type the password in the wrong order or have misspelled it in some sort of way. But in preferences im sure the issue can be solved.