Seven Deadly Sins / Nanatsu No Taizai Season 4?

Have looked at Netflix now the 3rd season to an end. Is there a continuation of it somewhere and if not, when?

There are not three seasons but two. The squadron listed on Netflix as Season Two is an OVA and only serves as a preparation to prepare for the real second season. For the manga template also the end would be announced. This suggests a decline in popularity which greatly reduces the chance of a real third season.

However, there's still room for improvement and enough material for it. Just because a manga stops does not mean that it sinks so low. Think already that one more season would be safer than a fourth let alone nothing comes. But the last season is also just since the Winter Season 2018.

Outside. And thus still air up

So far, no third season has been announced (the third season on Netflix is actually the second and the season before an OVA series).