Fixed the problem by creating a floating rule that allows outbound connection to 142.250.0.0/15, which is the block of IP addresses used by 1e100.net, the umbrella network for Google's servers. What appears to have happened is that Google changed the DNS entries in the Denver area to route traffic over their network. Several common pfBlockerNG blocklists contain 1e100.net, which I'm sure has plenty of servers that host malware. Although I allow the outbound connection, the inbound WAN rules are still in place, which should block the garbage. Fingers crossed. Thanks very much to the illustrious BBcan177 for his Saturday night patience and assistance!