Maybe he feels that the Order is keeping secrets from him. In many fanfictions, Harry can be a character who values honesty and when he discovers that the Order, which he may consider an ally, is hiding things from him, it can make him angry.
It could be because the Order's actions put his friends in danger. For example, if their plans lead to his friends getting hurt or into difficult situations, Harry, being protective of his friends, would be angry at the Order for not being more careful or thinking things through.
Another reason might be that he disagrees with the Order's strategies. Harry has his own ideas about how to fight against the dark forces. If the Order's approach seems too passive or too risky to him, he could get angry as he might think they are not doing enough or are making things worse.
If you want the clearest chapter reference, go to Chapter 117. Early on, Fragrant and cloyingly sweet potatoes and corn were out of the pot, and Qi...; later, the chapter leans on The searing heat made him grimace in pain, but he didn't let go, and he....
The best chapter pointer here is Chapter 124, "Officially Certified 250". It opens with Since there were too many points cards inside Jiang Li's barrel, Director... and closes on No need to repeat that number three times.] [Hang on, didn't Jiang Yan....
Chapter 123 is the strongest chapter-level answer because it starts from After He Yun also carefully rolled up her trouser legs and walked down... and follows through on Seeing this, He Yun chuckled softly to himself, then glanced at his own....
Look to Chapter 90 for the clearest answer. It begins with Watching He Yun gradually take control of a tractor under professional..., keeps building through Director Sun," Qi Tianyu, having finished admiring, started to complain,..., and lands on Jiang Li finally let go of Jiang Yan's arm..
The best chapter pointer here is Chapter 116, "Group Freeloading!". It opens with But before the audience in the live room had time to continue brewing the... and closes on Their old Jiang family never had such twisted genes in hundreds of years!.
The best chapter pointer here is Chapter 140, "Did Jiang Li Finally Crash?". It opens with In the evening, the setting sun was like blood, dyeing the entire earth a... and closes on I was just joking, just joking." Seeing that Wen Jiaojiao had no intention....
The best chapter pointer here is Chapter 134, "Being able to accompany Miss Jiang is my good fortune". It opens with After a brief noon rest, the production team was up to their antics again. and closes on [Are you kidding me, is Jiang Li putting on an act again?.
Look to Chapter 114 for the clearest answer. It begins with As time passed, the number of viewers in the live broadcast gradually..., keeps building through After a whole day of trending searches yesterday, the popularity of..., and lands on But just now, an uncle came and said not to give you.
If you want the clearest chapter reference, go to Chapter 112. Early on, These five people are supposed to be at odds.; later, the chapter leans on When did they become so in sync?] [I'm dying of laughter hahaha why is....
Look to Chapter 119 for the clearest answer. It begins with What is Princess Wen talking about?, keeps building through I can't understand a word?] [Is this some new meme?] [!!!, and lands on For some reason, he always felt there was a mysteriously calming power....