Windows disappearing when switching between apps on Mac

Disable Stage Manager in System Settings > Desktop & Dock.

Like dialabrain, I immediately thought of Stage Manager; since you say it is off, the other possibility is that you may have these applications running in different Spaces.

Launch Mission Control and see how many "Desktops" or "Spaces" you have.

If, for example, Chrome is on Desktop 1 and Word on Desktop 2, then switching will hide the other window(s)...

Click the Mission Control icon in the Dock. Desktops are lusted at the top of the screen.

Intriguing “ Windows Disappear “ ?

Using the “ Tiling “ effect introduced in Sequoia 

Tile windows on Mac

Change window tiling settings on Mac

Or, if that is not what you like or want 

Use ” Spaces in Mission Control “ 

➡️ Enter or leave Mission Control. ⬅️

• From a trackpad: To enter, swipe up using three fingers. To leave, swipe down. You can turn off or change the trackpad gesture in Trackpad settings.
• From a keyboard: To enter or leave, press the Mission Control key  or press Control-Up Arrow. You can change the keyboard shortcut in Keyboard settings.
• From a Magic Mouse: To enter or leave, double-tap using two fingers. You can turn this gesture on or off in Mouse settings.
• By dragging a window: To enter, drag a window up to the top of the screen. To leave, click the desktop. You can turn this feature on or off in Desktop & Dock settings.

If you enter Mission Control on a second display, only the open windows and spaces you’re working with on that display are shown.

Also See: View open windows and spaces in Mission Control on Mac - Apple Support

PeterR wrote:

Already disablled, so no help there.

Then apparently you meant something other than what you described.