Lowercase becomes uppercase, uppercase becomes lowercase
Try a different keyboard, it maybe a hardware error.
In fact, this is the keyboard that comes with my laptop, and when I type in lowercase, the upper case light doesn’t light up, but it lights up, and when I type in upper case, the upper case light doesn’t light up.
Do you have CapsLock enabled? That is designed to do what you describe.
There are customisation to how the CapsLock key works that you might find useful.
Look in your Settings for Keyboard and see what can be setup for Caps Lock key by your desktop software.
I don’t think it needs customization because it’s probably a bug and when I reboot it’s working again
Might be specific yo your hardware. I do mot recall anyone else reporting this issue before.