When the string is long, PHP returns null

[id0612]

I use the following string test to test, 307 characters, the maximum string that works, and when I increase the string beyond 308, I use PHP to unzip it and return null

901234567890123456789012345678901234567890123456789d8ZArwWLl0NIGdTTqXUVfuRXZvU3nTt13q62dibFFAUQQfvJQ3_AQd1pTVk4g4vu-3Yf9cvK6QQQuxH-DG9BU68M24fZVTlzvTWBrpqz3YFBItPiOxjdoHaJyFEuZbcjd8ZArwWLl0NIGdTTqXUVfuRXZvU3nTt13q62dibFFAUQQfvJQ3_AQd1pTVk4g4vu-3Yf9cvK6QQQuxH-DG9BU68M24fZVTlzvTWBrpqz3YFBItPiOxjdoHaJyFEuZbcj

My application scenario is JS compression, PHP decompression.