Unity of style is one of the basic rules of design. It is better to use the same border radius, the same shadow style, etc. on all buttons. Otherwise, the buttons look messy, and ruin the whole impression of the design.
There are exceptions to this rule, and they are buttons that are in the navigation of the site or app. Such buttons are logically separated from all other content and are perfectly normal to perceive differently than normal buttons within the content.
The destructive action should always be secondary and have less contrast than the primary action. This action does not need to be bright as it increases the risk of mistakes and accidental clicks.
In fact, the destructive button does not even have to be red at all. Delete, cancel is always a secondary action. So it might be a more low-key and quieter button.
It is better to place the destructive action in the opposite side from the primary action to prevent accidental clicks.
