The shortcut that used to open the command palette or trigger a capture does nothing, and you did not change any settings.
Chrome does not arbitrate shortcut conflicts. It gives a combination to whichever extension asked first and never warns the loser, so a newly installed extension can silently claim a binding. Note also that Cmd+Shift+T cannot be bound by any extension because Chrome reserves it for reopening a closed tab.
Open chrome://extensions/shortcuts to see every binding and its current owner, and rebind your combination there. The open-templates command ships without a default key precisely so it never collides; assign it yourself if you want one.