It's not an IPv6 address, it's a block of IPs in CIDR notation:
Blocking a single IPv6 address isn't very effective.BartVB created this issue in NodeBB/NodeBB closed Blacklisting an IPv6 range doesn't work #5879
Hello, is it possible to block global moderators and moderators from checking user IP? I searched all ACP and unfortunately I found nothing.
No, as viewing IP addresses are a core part of the moderation experience. Global moderators can access the account info page, and category moderators can view IPs per post in categories they moderate.
This is needed to see if particular users are sockpuppets, or other malicious types of users.