I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

https://codesandbox.io/s/pedantic-butterfly-fo30ni?file=/src/App.tsx

Steps to reproduce

1. Take Recharts Simple Bar chart example and open it in the codesandbox https://recharts.org/en-US/examples/SimpleBarChart

2. Upgrade recharts to v2.1.13 in package.json

What is expected?

Chart tooltip should not have a visible border if not defined.

What is actually happening?

The tooltip border appears. In Firefox browser its solid red color, in Chromium its solid black color. The border appears randomly and there is no way how to remove it with CSS.