Its supposed to switch to case sensitive when I type a capital letter, but for me it is now stuck in case sensitive. Restarting didn't help. Can't find anything in options.
Any way to get it back into case insensitive mode?
There are two different settings one is "smart" case sensitivity(see picture below)
Which means when you type anything that does not contain upper letter it's case insensitive but if you use any upper letter it automatically turns into case sensitive.
And second option which is probably what you have enabled is "classic case sensitivity"(see picture below):