If the focus indicator is not clearly visible, users may struggle to interact with checkboxes effectively using only the keyboard. This can result in users being unable to accurately select or deselect checkboxes, impacting their ability to interact with forms or perform important actions.

Actual Result:
keyboard focus is not clearly visible on selected checkbox controls, while navigating using tab key.
Observation: Rectangular keyboard focus is not visible on selected 'Select all, NA' etc. checkbox controls but it is visible on not selected checkbox controls.
Expected Result:
keyboard focus should be clearly visible on selected checkbox controls, while navigating using tab key.

source link- Excel Style Filtering in Angular Data Grid- Ignite UI for Angular (infragistics.com)