My approach is to create a pattern with alternations (|) that precisely match each of the target items. I've analyzed the items and grouped them into categories:

1. Datetime formats:
   - ISO formats with timezone: "2023-04-15T14:30:45Z" and "2023-04-15T14:30:45+01:00"
   - Slash format: "04/15/2023 14:30:45" and "2023/04/15 14:30:45"
   - European dot format: "15.04.2023 22:45:13"
   - Custom format with dash and dots: "2023.04.15-14.30.45"

2. IP addresses:
   - IPv4 addresses: "192.168.1.1", "10.0.0.123", "0.0.0.0", "255.255.255.255", "127.0.0.1"
   - IPv6 address: "fe80::1ff:fe23:4567:890a"

3. Usernames:
   - With underscore: "user_123"
   - With dot: "admin.root" 
   - With hyphen: "api-user", "task-scheduler", "backup-system"
   - Simple: "guest"

4. Email addresses:
   - With plus sign: "help+subscription@company-name.co.uk"
   - With underscore: "sales_team@example.com"

I've created a regex that uses alternation to exactly match each target item. Since some items use characters that have special meaning in regex (like dots, plus signs, etc.), I've escaped them appropriately. The alternation ensures that only exact matches are captured.