Apply percent discount with discount amount more than the price of the item

[toniagency82ed]

I can not reproduce this issue, so it must be either some custom code or extension that you have there touching the cart rules logic calculation or maybe the difference comes in your specific configuration settings.

What comes to mind as possible configuration settings that could impact the amount of discount you see there are under Stores > Configuration > Sales > Tax > Calculation Settings, particularly parts related to "Apply Customer Tax" - before discount or after discount and "Apply Discount On Prices" including tax or excluding tax.

But more likely some custom code or extension you have there is causing this.