Symptoms

A prompt, similar to that of the below image, shows up when an attachment is added to any record. It may also be observed that the prompt only shows up for certain users/ instances.

Cause

This is a feature and not a bug.
The prompt shows up when the accessibility enabled feature is activated for the logged in user. 

Resolution

Accessibility can be enabled or disabled using the system settings (cog wheel on the home page located on the right top corner of the screen). It is available under the General section of the system settings:

 

The user preference corresponding to the feature is glide.ui.accessibility. Admins can modify the user preference and make it a system preference to set the intended default accessibility for all users.

Additional Information

Following is a document on how to enable accessibility features on the now platform:

https://docs.servicenow.com/csh?topicname=c_SetUpSect508ComplianceFeature.html&version=latest