You can definitely over-practice. Our brains have limitations - you cannot endlessly force-feed new information to your brain. It will not be properly absorbed and digested, and you can get a sort of "brain freeze" just as you are describing: New information will not be properly absorbed, and even old material can suddenly become difficult: You brain is exhausted.
The situation you are describing happens to me not that infrequently - I am not a young man and I practice with a great deal of discipline and make demands on myself. Every few months, things might go 'haywire'.
When that happens, the best thing to do is take a break. Maybe just take off a couple of days and read a book or watch a movie or take a walk instead of practicing.
If you don't want to do that, cut back your practicing hours, lay off from trying new and difficult material - just relax and play for an hour or two for pure enjoyment, and when you are well rested.
I am a bit worried I fell in the trap of over practise which makes you
practise “wrong” by adding the wrong memories..
I don't think that is a great concern. You are describing what I think is brain exhaustion/over saturation - you will not add wrong memories - you just won't add anything.
especially if I am tired(which I can appreciate!)
I know it is difficult, but try to avoid practicing when you are tired. That's how such problems begin - you are tired, you try too hard in order to overcome the tiredness and your brain and body begin to rebel and shut down.
Practicing and learning music is not so easy for most of us (it certainly isn't for me) - you should be refreshed and relaxed when you practice and learn. I often manipulate my schedule so that I don't have to practice when I am tired. For example, instead of practicing in the evening, I will go to sleep early, wake up early and practice in the morning - HUGE DIFFERENCE.
One might even consider it disrespectful to Music if you practice when you are tired or "brain fried" - Music is important: It deserves your best efforts.
Another way of looking at this - not really a contradiction at all - is that your brain is sending you a message:
You have accomplished a great deal, now give me time to digest it well
before moving on.
Often after maxing out and taking a break as described, when you come back strong you'll find that things you were struggling with have become easy, and new ideas begin to flow.