Thanks for all the comments, this Jam was a lot of fun! I'll address a few of the issues that people have mentioned here:
Text readabilityI got a 4K monitor a few weeks ago, and this is the first game I've written since then. It's pretty readable for me! But I really should've tested it more at 1080p and lower, as it's a lot more difficult to read there. Originally I was going to have no labels and rely on different shaped bottles and coloured liquids, that might be a better approach if I can get the potions to look different enough.
Balancing
It's too hard to begin with and that really needs fixing, I didn't have enough time to work on this aspect. I think I'd want the potions to drop a lot slower at the start, and reduce the number of different potions to a smaller sample. Then have the drops speed up and increase the number and variety as the number of recipes completed increases.
Loading
I forgot to preload the game from the menu! And I should've preloaded the shaders and some of the particle effects too. Lack of testing in the browser was the problem here.
I'm planning to continue working on this game after the Jam judging is complete. Hopefully I'll address all the above issues and get to add some additional features like special potions that will give time bonuses and other positive effects (and probably some negative ones too!)
The feedback is greatly appreciated.