Thanks for taking the time to play my game and to leave a comment.
The dead plant was originally going to be an oasis-specific object (waters geysers). However, as the oasis side had tree-platforms, I felt that I needed a helper object/obstacle on the desert side to keep the balance between the two. The dead plant was supposed to be bramble or a thorny plant that causes an upward movement due to being pricked by the thorns like in old cartoons (think Looney Tunes when a character is poked). Admittedly, my art work and the lack of player sprite change doesn't convey this aspect well. It's also why the final level guides you to a deadend where there's nothing to try out except the plant.
The water sound effect was taken from an asset pack. I had initially only wanted an effect for the initial entering of the water, but the tilemap collider that was used for the water was constantly triggering the effect as the player moved through it. Because of that, I ended up selecting the "moved through water" effect instead of "entering water" effect. In hindsight, I should have programmed in the option to set what "type" of water the player is entering and select the appropriate sound effect based on that setting.
Thanks for the comment about the music. It was fun learning how to use boombox.co, and making the function to switch over the tracks at the same timestamp when the player switches dimensions.