A low-tech solution to a high-tech problem!
Sorry to hear that!
This script only hides the button and doesn't apply any DOM manipulation nor click that button, so I have no idea why is automatically pressed... Are you sure this script is responsible for that?
Though, I can add an opt-in hijack to prevent event listeners to be added to the Miniplayer key ("i") and "disable it" if you want. Note that I don't know how this "native macOS player" works, but it will probably work without affecting other extensions/keybinds.
I have installed this script for one sole purpose—to disable miniplayer.
Miniplayer button, or autoplay, or Cast to TV button never bothered me, since I'm using native macOS player instead (using other plugin to enforce that).
But the miniplayer itself really annoys, it kicks in automatically and react to the “I” button press.
This plugin did not fix that for me. I know that this is probably not what it intends to do, but anyway, full annihilation of miniplayer would be really nice.