The series was released all-at-once on Sky UK's VOD platform and Now but the series still airs weekly on Sky Atlantic UK. The weekly air dates are correct.

If all the episodes can be watched in a legal capacity why is that not considered aired?

@raseon said:

If all the episodes can be watched in a legal capacity why is that not considered aired?

Because episodes 2-7 were made available early on the Sky website but haven't aired yet on Sky Atlantic UK. That's considered a digital preview and those are ignored on TMDB.

For TV shows that air on linear TV, the air dates should be the day the episodes air on the actual channel.

So will they still be considered “digital preview” on April 5 when all Episodes will be available for streaming worldwide yet according to the dates you’ve placed several episodes will still not have “aired”?

@raseon said:

So will they still be considered “digital preview” on April 5 when all Episodes will be available for streaming worldwide yet according to the dates you’ve placed several episodes will still not have “aired”?

If by April 5 you mean the show's release in the US on Starz, Starz is also airing one episode per week so they will be 5 episodes behind the UK.

The air date field is for the date the episode airs on the network. The network for this show is Sky Atlantic UK and they air the show weekly. As of today, only the first two episodes have aired on Sky Atlantic UK; episodes 3-7 have not yet aired.