When using session windows, the state of slot 1 keeps growing

This will happen no matter how much parallelism  I set, and it will always be in slot id 1.

I have set different parallelism (50/100/120/140).

The amount of data received is about the same as other slots, but the state is much larger and growing.

The same code is running normally in the test environment (parallelism is 10).

Thank you for your help~