Yes, it seems to be working. Now I only have 127.0.0.1#5335 as an upstream DNS server and these are the results:
pi@pi3:~ $ nslookup bloomberg.com 127.0.0.1
Server: 127.0.0.1
Address: 127.0.0.1#53
Non-authoritative answer:
Name: bloomberg.com
Address: 69.191.252.15
Name: bloomberg.com
Address: 69.187.24.15
And the log:
pi@pi3:~ $ grep -C3 bloomberg.com /var/log/pihole.log
Sep 17 18:36:40 dnsmasq[17154]: reply coronacache.home-assistant.io is <RRSIG>
Sep 17 18:36:41 dnsmasq[17154]: query[A] data.mistat.intl.xiaomi.com from 192.168.1.134
Sep 17 18:36:41 dnsmasq[17154]: gravity blocked data.mistat.intl.xiaomi.com is 0.0.0.0
Sep 17 18:36:41 dnsmasq[17154]: query[A] bloomberg.com from 127.0.0.1
Sep 17 18:36:41 dnsmasq[17154]: forwarded bloomberg.com to 127.0.0.1
Sep 17 18:36:41 dnsmasq[17154]: reply bloomberg.com is 69.191.252.15
Sep 17 18:36:41 dnsmasq[17154]: reply bloomberg.com is 69.187.24.15
Sep 17 18:36:41 dnsmasq[17154]: query[AAAA] bloomberg.com from 127.0.0.1
Sep 17 18:36:41 dnsmasq[17154]: forwarded bloomberg.com to 127.0.0.1
Sep 17 18:36:41 dnsmasq[17154]: reply bloomberg.com is NODATA-IPv6
Sep 17 18:36:42 dnsmasq[17154]: query[A] api.ad.intl.xiaomi.com from 192.168.1.134
Sep 17 18:36:42 dnsmasq[17154]: gravity blocked api.ad.intl.xiaomi.com is 0.0.0.0
And not only these look OK, but the whole network seems to be OK, too!
Thank you very much for your time!!!! Much appreciated!