Keyboard Malware Attack?

Some keys/ key combinations that were previously working are no longer working. It has affected the backspace key and the Right Shift Key (RSK). Occasionally when typing, text might start being erased from nowhere. Key combination like the RSK and up arrow do not work, but the RSK with the down arrow works. Other independent RSK function work.
I thought it was a 'normal' malware attack so I fully scanned my system using a windows defender but the problem still persisted. I then formatted drive C (containing the OS) and performed full re-installation of all apps. This changed nothing.

It is a laptop so there does exist a slim chance that a wrong keyboard was installed...but either way, it was functioning properly for quite a while until this situation. Language is no issue since the change in behavior occurred when the computer was still in operation; months after the last program/OS installations done on it.