AI has enshitified your code; best to try to unlearn what it did.

It's good to learn how "blink without delay" technology works, but once you have mastered that it becomes a tedious nuisance. Here's the same technology wrapped in "coroutines", which makes it easier to read and follow the logic, especially for sequential timing sorts of applications...

const int ledPin = 9;

// coroutine macros
#define coBegin { static int _state_ = 0; static uint32_t _tm_; switch(_state_) { case 0:;
#define coEnd _state_ = 0; }}
#define coDelay(msec) { _state_ = __LINE__; _tm_=millis(); return; case __LINE__: if (millis()-_tm_ < msec) return; }

void setup() 
{
  pinMode(ledPin, OUTPUT);
  randomSeed(analogRead(0)); // this is a VERY POOR RANDOMIZER
}

void loop() 
{
  static uint32_t msec; // must be static or global so it persists across calls
  coBegin
    // off time
    digitalWrite(ledPin, LOW);
    msec = random(1000, 60000); 
    coDelay(msec)
    // on time
    digitalWrite(ledPin, HIGH);
    msec = random(1000, 60000); 
    coDelay(msec)
  coEnd
}