I'm not sure how common this problem is, but I'll try to explain. I'm a right-handed user using a Pixel 2 XL and have noticed in the past few weeks that I've hit the Call/Video Call function way too often in Direct Messages. These buttons are placed in such a way, if you come up short on swiping down the status bar at the top of the screen that you may inadvertently hit these buttons and start a call that's untimely for either party.
If I may make a suggestion to move these to the their own drop down or just into the menu on the top right to alleviate this issue. Alternatively, could this be an option to simplify the UI in the settings for Mobile just to increase screen real estate.