pi@raspberrypi:~ $ sqlite3 "/etc/pihole/pihole-FTL.db" "SELECT client,domain,count(domain) FROM queries \
> WHERE client == '192.168.0.101' \
> GROUP BY domain ORDER BY count(domain) DESC LIMIT 10;"
192.168.0.101|data.mistat.india.xiaomi.com|6279
192.168.0.101|www.googleadservices.com|3883
192.168.0.101|googleads.g.doubleclick.net|3871
192.168.0.101|data.media-lab.ai|2981
192.168.0.101|app-measurement.com|2049
192.168.0.101|youtubei.googleapis.com|1893
192.168.0.101|ssl.google-analytics.com|1515
192.168.0.101|www.google.com|1408
192.168.0.101|connectivitycheck.gstatic.com|1248
192.168.0.101|data.mistat.intl.xiaomi.com|1083
I should tell here that if top clients is an historical list (and not just top client in the past day) the results are probably justified in the sense that a recent router restart gave the IP 192.168.0.101 to another of my device while it was allocated to some other device for about 4 months now.
The number 10943 before it can signify the sum of queries from this IP address 192.168.0.101 which was allocated to 2 devices (once before then another device with high usage after router restart).
Also, I tried your link : How do I increase PHP's memory? - #3 by deHakkelaar.
And increased the memory allocated to 512 MB, now the top query is also getting populated 
I am highly thankful for such a short turn around time from your end and also the excellent support.
I checked that conditional forwarding is turned on in Pi settings, I use my router as DHCP, would you recommend turning Conditional Forwarding to off?