IPv6 is not better or worse than IPv4, it is just a different writing format for the same thing that allows for more unique combinations.
The bad thing is that people do not understand how it works.
With IPv4, most people would know that 111.111.111.1 is in the same subnet as 111.111.111.2 and that this could be bad.
With IPv6 it is the same thing but with a string like this 2001:0db8:85a3:0000:0000:8a2e:0370:7334 nobody knows what is good or not because they have no clue.
A provider gets assigned a block and can generate millions of different IPv6 addresses and users think it is unique.
Big companies like Facebook have figured it out already how it works, they know immediately what IPv6 belongs to which provider and ban you quickly if you use the same subnet.
Don't let yourself get scammed with IPv6.