IntelliJ IDE suddenly started showing "meta" based shortcuts in windows

Meta is NOT a typical Windows key. So possibly you are not using Windows key map. You can change current key map in this way: File -> Settings -> type "Keymap" to search Keymap setting -> change your key map setting.

From @fnl comment: Meta isn't a key typically found on modern machines at all. It's a leftover from Sun's demise, at best. Apple's computers have Control, Option, and Command (aka. Apple Key), much like Window's machines have Control, Alternate, and the Windows Key. So in fact, it's like the Windows or Apple Key, but Meta is so important to some that you often get offered to "replace" the Option/Alt Key with Meta's functionality.