For some reason my cellular network ISP doesn't throttles the access to Open DNS after exhausting their daily usage cap.

My provider provides a limit of 2GB/day. The speed gets unbearably slow after exhausting their data caps. The weird part is after running out of daily cap there is substantial difference in the ping delays between every domain except Open DNS 1.1.1.1 and the default gateway of the provider.

Did they just forgot to pull the switch on Open DNS or it's something else ?