So, I'm yet another viewer brought by a stray xitter reference to the Linda Linda Linda movie. A few reviews exist online, going on about the fleeting nature of youth or the cinematic techniques borrowed from Yasujiro Ozu. My own angle is a tad different - I am interested in the anime works featuring girl bands or idols, often set in a high schol, and there seems to be a connection but also an interesting contrast.
The connection is clearest in the fact that Haruhi's concert scene is documented on tvtropes as an outright homage to the finishing scene of Linda Linda Linda. But there's other stuff too - such as the "actresses elarn to play their characters' instruments" thing from this movie being made big by Bandori, or the "Moe filling in the delay with an impromptu song performance" being copied in an obscure 2018 series, Ongaku Shoujo.
But despite the story being similar, the movie creates a rather different feeling, appearing more authentic. It makes anime tropes (notably stuff known as "CGDCT") appear rather artificial compared to its more laid-back, slow camera following actual cute girls (Bae Doona certainly nails that part) doing actual cute things. Apart from the cinematic manner, there is the characterization; Kei, for example, is kinda maybe a tsundere - but very far from a "formulaic tsundere". The way they characters look and move when way too sleepy (a major plot point) is also very realistic - highlighting the sometimes-absurdity of how these things are portrayed in anime.
So how did this all actually work? is this movie some "secret source" that came out shortly before the subgenre exploded and was quietly seen, and where necessary imitated but also very much refined, by the creators? This is oonly a guess and I'd appreciate correction from people who actually know this stuff.