MacBook Pro shuts down at 70% battery level, why?

Hey, I have a MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports). Recently, I have started facing this issue. Last week, my MacBook Pro shutdown at 50% battery level and it won't turn on. Today, it shutdown at 70% battery level, and I can clearly see that 70% of my battery is remaining.

When I tried powering on, my MacBook Pro display showed a battery with low power (battery with red indicator) with a plug. The one which we see when there's no charge left in an iPhone, but in my case, I have 70% of battery left.

I have checked my battery health, and it says:

•   Charge Remaining (mAh): 2837

•   Fully Charged: No

•   Charging: Yes

•   Full Charge Capacity (mAh): 3782

  Health Information:

•   Cycle Count: 270

•   Condition: Normal

When I connected my adapter, my MacBook worked again and battery started charging from 70% to 100%. My battery hasn't reached it's limit as Apple website said, it needs to be 1000 and mine is 270. I'm an iOS Dev, so I always keep my MacBook plugged in. Can anyone help me with this issue?