MacBook Air tech

I am very please the more Language Switch Keyboard Layout Expert has joined in @ Tom Gewecke

Worth testing as suggested with external KB.

As for Screen Protectors - definitely Non. The Machine Tolerances between the Chassis of the computer and the Screen when it is closed is sooooo small that even a seemingly little object on the Screen or keyboard may damages

The only thing I use is the Original Paper covering that was on the Keyboard when new.

Appealing pressure to the Lid when closed or for that matter closing / opening the Lid, by using one Hand on the corner of the screen, the pressure and additional Torque ( Relationship between force F, torque τ, linear momentum p, and angular momentum L in a system which has rotation constrained to only one plane (forces and moments due to gravity and friction not considered). can crack the Screen

Is this a New Issue ? If Yes, what exactly changed on this computer ?

Is this an Old Issue ? If Yes, what actions has the user taken to fix this issue ?

Understand, we are all working Remotely from all around the world. Therefore, we do not have the On-Hands experience the User ( you ) has with this computer.

Reliable , accurate, details and context will really help to pinpoint a possible solution.

If the user is certain the Key itself is malfunctioning as in a Hardware failure it is needing Evaluation or replacement

You are welcome and thank you too.

Do come back to the Apple Support Communities ( ASC )  in the future, if / or when additional questions may arise

And a personal thanks to @ Tom Gewecke for joining in.

philippa155 wrote:

When I ordered it I remember selecting the GB keyboard and am wondering if that is why the left shift key has never functioned - extra numerals on the keyboard perhaps.

No, that's not the reason. Most likely it was defective. You can always try an external keyboard (doesn't have to be from Apple) to test that kind of thing.

Welcome again 😀 from Canada 🇨🇦