First thing, before I got into the game, the settings menu did make me laugh with how it has so much empty space for only one actual setting (for the video options, that is). The settings menu wouldn't allow me to close it either, forcing me to refresh the browser before I could actually play the game; no idea if this means settings can't be saved once changed.
Once in the game, I noticed the zooming being "anchored" on the top-left corner, and it was slightly difficult to get used to peculiarity. It'd make more sense if it was anchored to the center of the display, or to the cursor's current position. The panning was also a bit slow while zoomed further out, and would require me to drag the full available cursor space a couple times to get a decent survey of the area. Its speed is great when zoomed in closer, though.
A detail I really enjoyed was the tiny leaves fluttering around across the otherwise empty blue void of the background. Some subtle clouds could also help to keep it visually stimulating while matching the theme and aesthetic. However, the UI on the right seems to have some unusual behaviors. When I use right-click to deselect an object, the pertinent button stays highlighted as though I have it selected. The research lab button changes color when hovered (and while another item is selected), but the others don't share this behavior (aside from the button text, which changes slightly).
Additionally, it was unclear how the wood resource was to be used until I purchased a research lab and realized that the associated cost for the lab was in wood, not leaves. The game description on the itch.io page doesn't seem to mention this (I read it over a few times to be sure before commenting). It'd be useful to denote that it requires wood to purchase by putting a symbol by the listed price on the button (and a leaf symbol for the other items)
One thing that I really enjoyed was the realization that each subsequent research lab offered the same upgrades, but at the original price points, so I could strategically buy extra research labs, buy the +1 grass tile spawn upgrade, and really feel like I had employed strategy to help me win. Final recommendation: It'd be cool if the game explicitly displayed how many resources each tree grants you when planted.
I apologize if some of these things were already noticed, but I wanted to be thorough in case it wasn't known. I also didn't experience the issues which the other commenter reported.