If statement using millis function in Attiny 85 does not work as intended

The code literally works when you get the time in milliseconds and it's divisible by 100.Therefore, if the next time runs less than a millisecond after one split, it will continue to be a hit, and on the contrary, if you are unlucky, you may not be able to.

Therefore, if you want to implement it as intended, you need a code that records the last time you ran it, and then runs it again after more than 100 milliseconds.Here's the reference code.

static int last=0;

int now = millis();
if((now-last)>=100){
    last = now;
    // TODO: Write here what you want to do every 100 milliseconds
}

There is a high possibility that this code will not work as it is, so please rewrite it accordingly.