Some on-the-fly observations:

1. Misspelling ‘wWhen’.
2. Controls are QWERTY-only instead of layout-independent (not easy for my AZERTY!).
3. Is it expected that the lawn mower goes behind the floor if you exit the grey area? It sounds like it is, but the fall is slow.
4. The concept is interesting! :)
5. I am not entirely convinced as to the connection with the constraint, although this is debatable.
6. I like how the level select interface unveils progressively.
7. Is there a key to restart a level? It would be useful (instead of having to jump off the edge of the level).
8. The score adds speed to reflection. Remark: if the player were forced to get a perfecly cut lawn (which is not the case here!), then tile-based movement would have perhaps been a better choice, since the controls are not that easy to master.
9. About the controls: I am wondering whether allowing continuous increase/decrease of speed (instead of step by step) would have been more practical; I am not sure.
   I think having the speed indicator also in game would help gauging the speed more precisely, especially for stopping.
10. Falling out of the area is a bit horrible. XD I would have preferred walls to contain the player, but maybe you wanted an extra layer of difficulty through this.
11. Level 5 seems untitled.
12. I like the particle effect for mowing. :)
13. You can mow diagonally (ie skipping a tile that is aligned vertically or horizontally with the previous tile); it may be expected. In a ‘perfect-puzzle’ setting, this could be a problem, but not here.
14. ‘I got hit by the 'rona fever (which does exist, see Stefan Lanka and David Crowe for example)’
    I also submitted too late to Mini Jam 110 (for another reason), so, I can relate. The most important thing is to have created the game. :)

I like the concept in itself and context (I don’t recall playing a lawn-mowing game before, although some may exist!); I am just wondering whether playability could be enhanced, and I also think the connection to the limitation is not that strong (once again, this could be discussed).
It could surely be extended with other interesting mechanics, such as different types of grass (e.g. tiles that you have to mow several times), allowing the player to spend his score/money on upgrades for the lawnmower, and so on. :)