New comments about the balancing as well
The layout of upgrades in the black hole is... Somewhat questionable I feel like? Some upgrades are ridiculously powerful while others feel weak. Seems like a case of "Just hope you choose the right one" on the first few resets which might be odd.
Overall ignoring the bugs not a bad game for first submission. I'd recommend moving all variables into a game object (Say, instead of star1Power = 0, star2Power = 0 etc, have something like let game = { star1Pow: 0, star2Pow: 0, ... })
This allows for easier saving (You can do JSON.stringify(player) to get the object to string conversion, then save the game using the localStorage API which you can find more info about on google. To retrieve the object again you can use JSON.parse(string))
I'd also recommend moving the javascript into its own file to not clog up the HTML which makes things very messy. You can have, say, <script src="game/js"></script> and then have a game.js file in the same folder as index.html.