Under Mining Fatigue, the attack indicator is shown when crosshair is aimed at an entity despite not holding a tool

This is the crosshair when you are looking at an entity when holding a tool. When you aren't holding a tool, the blade/indicator under the crosshair is absent. However, with mining fatigue, the indicator is always there when looking at an entity even though you aren't holding a tool.

Steps to Reproduce:
1) Look at an armour stand holding nothing

2) Run 

/effect give @s mining_fatigue

3) Notice that the attack indicator appears