"Fire And Blood" writer George R. R. Martin officially confirmed that the House Of The Dragon series will be completed in four seasons, and each of those four seasons will have ten episodes each. It was mentioned in his blog like this.
"It is going to take four full seasons of 10 episodes each to do justice to the Dance of the Dragons, from start to finish."
Apparently, they are trying hard to give a fair ending without rushing like at the end of GOT.