After KB5072033, my app starts, then is gone

I developed an app using Borland Delphi that has run successfully with no changes made since 2002.

The app does NOT make any use of the internet, only local files accessed using the Borland Database Engine.

The app has worked under a variety of Windows versions, until the December 12, 2025 Security Update (26200.7462).

Since that update was installed, launching my app results in:

• Tab for the app appears on the TaskBar
• App splash screen displays, with initial progress message
• Splash screen disappears, but instead of the main app window appearing, no window appears, and the tab for the app disappears from the TaskBar
• Task Manager no longer shows the app as running.
• No error message or warning appears.
• File Manager shows that 7 database files out of 54 were opened and closed (their "modified" date is updated).

I have tried
- running under a variety of compatibility modes (Windows 7 was preferred), as well as not using any compatibility mode. Same result.
- un-installing the security update, but the un-install "fails".

Any assistance you can provide is appreciated.