@AD2011 Are you facing some type of issues while using the applications which you generally use or while doing Gaming (if you do), If not, your connection likely to have any issue with it. But, if you are facing issues, Checkout below steps to see
Try to check if other
DNS like
Google, Quad9, BSNL etc. If they are giving stable latency, it can be BSNL end issue with Cloudflare. Restart your
router once and see if it fixes or not.
For 1.1.1.1 DNS to fluctuate, It can be various reasons. Like :
1. Connectivity : Not stable connection with electronic device. Try to use LAN or 5GHz wifi. If you are using, good

2. Stability : Looks like your connection is stable. Rx & Tx power are perfect. Temperature is Appx. 50*C which is bit high but routers can handle it mostly.
3. Backend issue : You need to ask BSNL Officer whether there is some issue at backend or not. Mostly, Backend issue is the reason for higher latency at Cloudflare DNS.
If you think issue is still there, Better to submit complaint to BSNL and see if it fixes. If not, You can also try to lodge complaint at
BSNL|PGRMS