If you're using your iPhone often as a gaming device you need to test your iPhone for that purpose as soon as you get it. My overall point to you is that you incur a lot of waste and further risk and aggravation if you dismiss your device the minute you find out it's not a TSMC iPhone.
So see my advice to the other member about testing your iPhone against your own usage standards. Think of the most demanding scenarios you're likely to realistically run into at some point in your ownership and see what kind of performance, battery life, heat dissipation issues you run into. Evaluate THAT. That's concrete, that's what's in front of you. If it's a good result that you can easily live with, keep it, especially if everything else about the device meets your standards. Be honest with yourself, don't sit there and think "Oh but if it had the TSMC chip in it, it would be even better."
Due to variances in the manufacturing processes there is no guarantee you won't still end up with a rather lame example of a TSMC chip. So even if you do find you got the TSMC chip, test the device anyway. Make sure it meets your needs. But be honest about it and don't set unreasonable expectations.
For example, it doesn't matter which chip you have, FB app will eat your battery for breakfast, lunch and dinner!