Whenever I have code like this:
'''
class A:

    def a(self):
        print("a")

    def b(self):
'''

Even if I have just pressed shift-Tab to go back an indentation level, as soon as I start writing the definition of function b, it gets indented to be inside function a. The same happens if I correct indentation afterwards, and then correct the line, its indentation level gets bumped up again. This is unbearably annoying.

The menu Tools>Indentation is indeed in "Python" mode. So this might be a Kate bug, dunno.