If you look carefully, you can see the grid lines as well, which I'm not sure if I can hide but honestly I kinda like it cuz it's unique and tells people how it's made
If you colour the grid lines the same colour as the background they will disappear. That's what I do at least. On Excel you can actually remove them completely iirc.
Yep; I've been doing graphics in google sheets and microsoft word for way too long lol; when I graduated from High school we had like a day where we could put up memes around the IB building about our IB teachers and I made them all in Microsoft Word which is somehow more sacrilegious lol.