System Information
Operating system: Windows 10
Graphics card: Nvidia RTX 2060

Blender Version
Broken: 3.0.0 Alpha, 70fbdcb6bf51, master, 2021-08-25
Worked: 3.0.0 Alpha, 5ef3afd87c54, master, 2021-08-24

Short description of error
Selecting through diferent objects in the outliner unexpectedly adds those objects to the current selection (without pressing either the shift or control key).

Exact steps for others to reproduce the error
Open Blender (Factory startup)
Add multiple objects (2 or 3 cubes should be enough)
Select an object with left click through the outliner
Select another object with left click through the outliner (without holding the shift or control key)
Second object gets selected in addition to the first one (repeat as desired to add even more)