new tropes have definitely been codified.
Honestly I don't think this is true at all. Bloom Into You is a well written and deep series but it doesn't do anything thematically that other series haven't done in the past. What it does is tie a lot of those preexisting themes together and does them well in the span of a single narrative. This is not a bad thing, stories do not need to be unique to be good and/or enjoyable. Indeed, they don't even need to be well executed either.
i'm not talking about themes really. i agree, bloom into you doesn't like, revolutionize storytelling with its themes or anything. i think at its core the themes are pretty clear and straightforward, and i think the way they're executed on is what makes the story so good, is what gives it such complexity and depth. it's those tropes that i'm talking about, the sayaka character, a watchful best-friend who's one leg of the love triangle and whose love is doomed to go unrequited. the touko and yuu characters, they have an uncertain dynamic for most of the story--and sure that's common enough, this is literally a staple of romance stories. but they're specific in that it's a senpai/kohai relationship, there's love at first sight (basically), one of them doesn't really understand love, and the other has trauma and doesn't want her love to be reciprocated. those last two are the barrier to their relationship, that's where their character arcs are.
I feel like all these tropes were already very popular in older yuri stories, waaay before Bloom Into You. The tropes you listed can all easily be found in say, Strawberry Panic lol. What Bloom Into You did well was give a more realistic and deep portrayal to these tropes. Like you said, it's how Bloom into You was executed that made it good, but yeah, hard disagree on these being tropes created by/made popular by Bloom Into You.
I don't really feel like this series is similar to Bloom Into You at all. It has a lot of common tropes as well (I mean what school girl yuri series doesnt?), but aside from the unrequited best friend role (which a lot of series have), this has a completely different theme, story and character relationship. I actually feel like Honami doesn't resemble Sayaka at all aside from the "seemingly unrequited love" part. I think people just think of Sayaka first because Bloom Into You is a lot of this generations' first introduction to a proper "school girl yuri" series.
I actually think it's kinda funny how you can tell what generation people became yuri fans by the examples of series they first think of. Just like how the first series that came to my mind when thinking of those tropes was Strawberry Panic (unfortunately hahahahaha).