This behavior did not happen with the previous xfce (4.13). It only started with 4.14.

Installing app-editors/vscode-bin after the latest xfce4 is installed, or even if vscode-bin was already installed, leads to the file manager panel icons launching vscode-bin instead of thunar.

Unmerging vscode-bin restores the normal behavior of the icons (thunar is launched) but reinstalling vscode-bin causes the abnormal behavior to reappear.

The application menu is unaffected, applications>accessories>thunar launches thunar regardless of whether vscode-bin is installed or not.