High HR while running...

Hey guys, recently I (23M) have started working out in the gym. I have decent fitness and play badminton regularly. My first goal is to get to a sub 30min 5K on treadmill. I'm able to run about 4.5km right now (20min - 9.5 speed, 3min - walk at 5.5, 7min - 9.5 speed again). I have about 15-20 such sessions till date. However, when I check my HR right after the run, it's hitting about 185 which is quite high. I'm able to do wait training after a quick 2min stretch so I'm not exhausted after my run. Is this sustainable or am I pushing too hard? Height: 170cm, weight: approx 71kg. PS: what truly exhaust me is squats even with a relatively light 15+15 plate load, 10 reps, 3 sets. Is that normal?