Getting high ping on low ping data centre (sydney)

I m starting to get 100 ping on low ping data centre. This problem started like 3-4 days ago. I have checked in with my ISP and there is no issue .I play valorant as well and i get 6 ping constant. I used to get 10-20 ping on sydney servers but now its constant 100 ping.. Some games it drops to normal ping and sometimes it goes to 100 ping..Even when the ping is high,it never fluctuates and there is no packet loss