microsoft source appears to disable itself after installing vscode update even though it's still enabled

i originally thought this was an issue with the vscode deb but it seems to be an issue with mintsources, see https://github.com/microsoft/vscode/issues/264431#issuecomment-3255905548

Steps to Reproduce

1. install the .deb from https://code.visualstudio.com/insiders/
2. enable the checkbox to add the microsoft apt repo during installation (i did this with linux mint's installer, not sure what that looks like in the CLI)
3. open "software sources" and check "additional repositories" and ensure the microsoft repo is enabled (might need to enable it initially, i don't remember):
   
4. wait for an update to vscode-insiders, then install it with linux mint's update manager
5. navigate back to software sources and see that the microsoft repo has disabled itself:
   

system info

• Linux Mint 22.2 Cinnamon
• mintsources 2.3.4

Start by reproducing the issue with Linux Mint 22.2 Cinnamon, mintsources 2.3.4, the VS Code Insiders .deb, and the Microsoft repository enabled through Software Sources. Use the linked VS Code discussion and the reported update sequence to trace why the repository becomes disabled; done means it remains enabled after a VS Code update or the cause is clearly handled.