It is shown that the eyes of Nora West-Allen the daughter of Barry and Iris in The Flash, Season 5 Episodes 19 & 20, glow red. It is also seen that the Reverse Flash has glowing red eyes. We know that Nora got that trait when she used the negative speed force made by Eobard Thawne aka the Reverse-Flash. What is the reason that these people get this trait but other speedsters show no such qualities, like glowing yellow or blue eyes?
Negative speed force has hate and anger, therefore their eyes are red showing anger and if somebody hurt them, they feel the pain from hurt in a higher level than the expectation; that is why Nora was trying to prove her abilities using Weather Wizard, Clown, and the Bee lady. If she was not using Negative speed force she was not that angry. Negative speed force brings power with anger. It brings a lot of negative tachyons that can be tracked and although not expected it generates a lot of speed. If you take a closer look you can see that Nora seems to be going even faster than her dad when she was affected by negative speed force; one other reason could be they go so fast with the negative speed force that their eyes are even burning from the speed. These are my opinions.