sub 20 5k whats wrong with me?

You are aerobically weak.

First and most importantly, run more. But don't just double the mileage, do it gradually.

Second, make sure to run really easy on most of the days, but once or twice a week run comfortably hard starting from 20 minutes and increasing to 40 minutes, whatever pace it might be.

Stop comparing yourself to other people and delete strava if you have to.

Jog 20-30 miles EVERY week, consistently. Do a 10 mile jog each week.

Use the 5K races as your speedwork.

If you enjoy running, just do it and don't worry about your times relative to others, just track them for yourself.

Last year I did 22 minutes for 5k, on about 5 mpw, age 50, 200 lbs, doing mostly sprint training. Random middle aged slobs are at your level, but that's irrelevant, just run for yourself and be consistent.

You might just be slow, relative to people here not the general pop.

To get faster run more and run workouts. Given your speed 50-60 is good, but long runs would help. Pick up a book from pfitz or Daniels and follow there 5k plan.

At your age, you can do it - even if you do happen to be "slower" than most runners your age. <20minutes can be done by a "slow" runner with good aerobic fitness. So, as others have said, you just need more miles.

The key question is what do your 50-60 km/week look like in terms of the speed and particular workouts? If you are just only jogging at 6 min/km, you will hardly improve. Have one interval workout (e.g. 5x1 km at your target 5K pace) and one tempo (5-6 km at +15...20 sec/km) per week and you will start getting faster. Long run is also important, but not so much for the 5K race.

With a well-structured training process 50-60 km/week is a good starting point. E.g., I am M64 and now at nearly the same volume as you, but still can make 18:28/5K.

Good luck!

You stated your weight in kilograms. You stated a height of 170. Are you 1.7 meters tall or 5'6" or 5'7"?

If you race sub-20 5K soon, great. If you do not, it does not mean something is wrong with you. If you cannot throw a baseball 60 m.p.h., do you assume something is wrong with your body or your training?

i am 170cm / 5 feet 7 inches.

In fact, I haven't done too many intervals before. Because I'm just coming back from injury a little bit and I'm going on vacation, so I want to somewhat make a plan of what I'm going to do when I get back.
I ran slow heart rate runs so as to keep my heart rate below 150 and more or less 137-149. The pace was very slow, because 6:00-6:30 per kilometer so 9:40-10:30 so 6:00- 6:30 per kilometer. If I ran faster i.e. below 6 per kilometer then I was running too fast and had more breathing. Faster means under 9:40.

It always seems to me that my legs carry me, but my breath doesn't allow me to keep running. I always slow down, and I slow down significantly. Especially in fast run

Stop training based on hearth rate but focus on pace.

2x per week do workouts or Race

All other days run easy or xc training or rest.

Regarding the 2 workouts:

1x Intervall or Fartlek (Speed):

30sec to 3 min runs at or faster then 3k pace alternating with 30 to 3 min recovery jogs, some examples:

10x400m with 2 min rest

5x800m with 90 sec rest

10x 1 min / 1 min off

6x3 min Uphill, jog down (3k effort)

The other workout

1x Tempo or Repetition (Strength)

20 min Tempo

4x6min 1 "

2x15 min Tempo 3"

Race

Good luck !