The writing does feel raw in many ways – punctuation, caps lock overuse, strange phrasings – and there are enough ESL-isms that it's gets distracting. A gentle but firm editorial touch to hone out the issues would help a lot; you can kind of tell that only the beginning was edited at all.
Besides surface-level polish issues, I'm kind of bothered by the game constantly explaining things. Emotions are sometimes needlessly stated (the "in my angry temper" feels extraneous when she has shown to be angry quite clearly), the flashback does a lot of slightly awkward backstory filling via characters mentioning facts about their daily lives, and the most interesting and evocative moment in the back half is told in monologue without any kind of visual representation of the events. It might be that there's just too much explained in general; the story being this short, the central conflict really needs to be in the spotlight for its emotional stakes to work. There's a decent amount of information conveyed, and you do get a sense of who these characters are (especially the protagonist, who has some good comedic bits), but their interactions in the main plot feel hard to engage with because it's all so hurried and abstract.
The premise is admittedly a creative one, especially in how it uses the game jam's theme. (A fungal network expanding wasn't my first thought when it was announced!) And while the central character design is not bad or anything, I really like the original mushroom dragon lady in your devlog – curse you, MAY WOLF's stringent rules.