It is just the default blocklist included by Pi-hole.
There are no specific recommendations, as Pi-hole is just providing the means to filter DNS traffic. Pi-hole's developers do not maintain any blocking lists, not even the default ones.
You are free to fuel your Pi-hole with any blocklists you can find (provided it matches the host format).
When looking for specialised blocklists, go for quality and content, i.e. try to assess whether a blocklist is decently maintained, and resist the impulse to just blindly grab any blocklist available for your home network. After all, it’s of little use having a domain on your block list that you never visit.
Steven Black’s hosts files do a good job in grouping blocking lists by topics and are also well maintained, and WaLLy3k’s Blocklist collection is a good starting point as well.