Edge-lit LCD backlights will always show some evidence of “backlight bleed” when viewed in a totally darkened room with the backlight intensity increased to high levels - any backlight bleed being invisible in normal ambient lighting conditions.
This is an entirely normal property of this type of LCD screen technology. Due to variations within the manufacturing process, there will be some variation between individual display panels. If you see visible stage-lighting effects in normal lighting conditions, you may then have a fault that requires investigation.
As your iPad is new, if purchased directly from Apple, in most countries/regions you have up to 14-days within which to unconditionally return your iPad for exchange or refund. If you have any concerns whatsoever, you would be well advised to make use of the opportunity while it remains available to you.
You can also have your iPad assessed by the Apple technicians at the Genius Bar of your local Apple Store or Apple Authorised Service Provider (AASP):
Genius Bar Reservation and Apple Support Options - Apple