This is not related to VSCode, as the same thing happens in any text input field across all apps (both on Wayland and Xorg, Fedora).
The issue appeared on my pc when I upgraded to Gnome 42, and I still can’t find a way to fix it (keyboard shortcuts don’t have any entry for Ctrl+.).
Edit: Found this post about this issue. Their fix is to run ibus-setup and to disable the ibus shortcut.