why redis ttl not working in exact time i configure

Question

I set TTL for 100 seconds which means, if I change something in database , changed data should be updated after 100 seconds, but what I am experiencing is new data is updating after 70 seconds not exact 100. how TTL works?

spring:
  cache:
    type: redis
    redis:
      time-to-live: 100000

this is my config