Yes, that part is indeed very normal.

But the fact that the country is a formal ally makes it, in my view at least, slightly different.

Of course, seeing as the US is in a defence pact with Turkey, I can understand that being ally can't mean absolute non-interference, but I feel that it gets problematic when we're talking about actual infiltration of a country's security services.

I think at least the Germans expected some restraint. I suppose if one thinks back, the Germans had a different view, being opposed to giving Turkey bad crypto; and I suppose that can be seen as them restraining their activities in an unreasonable way, at the same time, I can't accept that bribing/blackmail people on the other side is compatible with an alliance. Rather, with enough bribes/blackmail the result is a secret coup of the state whose personnel is being bribed or blackmailed, and I think if you view these things as 'normal' then you might even be blind to such a coup against yourself.