How many episodes did the second anime season of Nanatsu no Taizai have? Supposedly Nanatsu no Taizai is currently running the 4th season. There is a season aired in 2014 which had 24 episodes, there is another season aired in 2018 which had 24 episodes, 4th season is currently running, and I only can find listed 4 episodes made in 2016. Is that the second season or those are OVAs?  

How many episodes did the second anime season of Nanatsu no Taizai have?
As of 2019, officially in Japan, there are 4 series, but only 3 seasons:


Nanatsu no Taizai (2014): 1st season, 24 episodes
Nanatsu no Taizai: Seisen no Shirushi (2016): TV Special, 4 episodes, in which the last episode revealed the announcement for the 2nd season (see also Why is Nanatsu no Taizai : Seisen no Shirushi only 4 episodes?)
Nanatsu no Taizai: Imashime no Fukkatsu (2018): 2nd season, 24 episodes
Nanatsu no Taizai: Kamigami no Gekirin (2019): 3rd season, ? episodes


However, localization (and sometimes fans' opinion) make season count inconsistent or confusing, as Netflix considers each series as its own session:


The Seven Deadly Sins (2014): Season 1
The Seven Deadly Sins: Signs of Holy War (2016): Season 2
The Seven Deadly Sins: Revival of The Commandments (2018): Season 3
The Seven Deadly Sins: Wrath of the Gods (2019): Season 4