Does -21474836 mean someting?

It's only when I compared my friend's OP Comet and my OP Falling Thunder, noticed the DPS number on both panel is: -21474836.

It might be a threshold number of DPS calculation of POE2?

What you're seeing is called an integer overflow. It's a typical bug which happens when there's an attempt to assign a value to an integer that is greater than it's lower/upper bound.
The number you're seeing is called the lower bound of a signed 32-bit Integer variable.
The values a 32-bit signed integer has ranges from -2.147.483.648 to 2.147.483.647
An unsigned 32-bit Integer has a range from 0 to 4.294.967.295.
What you have seen is when your DPS goes above 2.147.483.647 it can no longer be stored in a 32-bit Integer container so it "resets" to the first lowest possible value. Same scenario would happen if you theoretically floored your DPS to the negative value -> then it would "round up" to the first highest possible value of the signed integer.

To fix this they need to either start using a 32-bit Long instead of the 32-bit Integer or Long Long if they need more space for DPS calculations.

Thnaks man~