For the first one it might be that your mouse is directly between the shop upgrades, the mousewheel is not working then and does not register. i need to add that to my to do list since this is also happening in other shops
the 2nd one is actually intentional, i put kind of a very soft retro filter over the game so there is a light bloom, those flickering spots and other things. if players do not want it i can remove or add an option to turn it off