This game is incredible. If this was a flash game that I found way back when I was a kid, I would probably have spent an entire weekend on this. I've loved the concepts of plants in tower defense because they don't look like they can just walk around like other TD's (BTD series is the biggest example). The music also goes really hard for no reason; it almost reminds me of Waterflame and I love it. The art is great and the concept of plants growing stronger over time works amazingly
I'm sure you've already heard your fair share of suggestions, so you can pretty much stop reading here if you want. But, here are some things I'll leave if this game is something you want to keep working on:
I'd like to see the 'growing stronger over time' mechanic a little more. It's a great mechanic because you get excited whenever a plant survives knowing it'll be stronger for future waves. So adding more stages that take a really long time to grow to and adding growth to the attacking plants would be cool
Along with the growing change, the insta-grow will have to be reworked a bit. It's good in the late game when there isn't time to wait for anything to grow and space is tight, but the problem is that the growing mechanic feels less rewarding and special the instant it's unlocked. Either make it only grow a plant by one stage each or have it only work up to a certain stage
I'm a 'less is more' guy, but I think a few more plants are kind of needed. Rockets are OP and there's not much room for variety otherwise. On top of nerfing rockets, I think the bare minimum is adding at least a closer range tower and a longer range tower
Picking up coins should be a bit easier. Either make the range bigger or have coins be picked up just by hovering over them (so you can pick them up easily while planting)
Have the late game difficulty ramp up more. Maybe it was just because I was playing on normal, but the late game got really slow really quickly and I think it's something to look into
Also, I'm just one guy. Don't worry too much about these suggestions and make the game for yourself first. Thanks for reading this far and I hope you have a good one