Keyboard malfunction progression: first ED, then FG, now T

I have a MacBook Pro (Retina, 13-inch, Early 2015), and since a while the keyboard is malfunctioning. At first the E and D keys problematic, then F and G, and now it's T. To be clear, the others are working normally again. So now it's only the T that is a problem.

Can somebody explain why this happens, how this works, how it will proceed and if I can do something about it now?

This is not the keyboard with the butterfly design, that had so many problems. This keyboard is from before that disaster.

Small update: when logging in, the T does not work at all, so I had to change my password. I tried many things, long hard presses, in each corner of the key. In the end I had to use an external keyboard to login. Now - logged in - the T works more or less.

Solution 1:

The entire top case assembly controls the physical mounting as well as the electrical connection. I would see if you need battery service for it and pay for that repair. Get two problems fixed for the same cost.

Without removing the battery, it may be hard to know if this is liquid damage / corrosion or mechanical issues like grit or just physical parts wearing / breaking or it's electrical connection on the USB bus. Also, a battery that expands could cause all the issues and need service.

I would get a quote for repair and then wait till you can't use external / bluetooth keyboard and they pay for a repair if it's not covered by Apple. Sometimes Apple extends coverage for batteries and keyboards, so it doesn't hurt to ask for a quote - sometimes the price comes back zero.