It hasn't changed recently. It's been literally years since I was successfully interdicted in my T-9. no idea what OP's problem is but I'd take a guess at trying to chase the recticule rather than intercepting its path.Has the interdiction game changed recently? I know that over the course of various updates it has been tweaked to be more or less difficult, but the last time I played, which was a while ago, they nerfed it all the way to "you will always win unless literally asleep at the wheel" levels. Since that seemingly final nerf, I've been able to consistently win the minigame even in a T9 with a laptop trackpad, and without much difficulty, either. (prior to this it was often a serious tossup as to whether or not I'd succeed. I'm. Not. Good.)
I haven't seen anything about changes to the interdiction game in any patch notes since then.
Would like to humbly suggest that you keep flying your build of choice and err on the side of trying to escape interdictions whenever possible. You will almost certainly win most of the time, at which point you won't have to deal with repeats for that particular mission; and so long as you have enough survivability to escape the rare occasions when "the game is rigged" as you say, then yes you'll maybe get a repeat interdiction from that same ship but I bet you'll win it the second go round.
Also I mean without interdictions in trading how much "game" is really left at that point?
The way to avoid being interdicted ten times by an npc is to beat the interdiction but OP's been told that several times already and his only response is to tell us all what an ace pilot he is. I guess I've just been lucky. For several years now.