Is 4 bags in the same style, but different colors too much?

Not at all. Functionality is so important in my opinion. If you are happy with the bags and how they hold your things, and just want colors to match your wardrobe, I think it's a great idea. I have a Fleuron bag that I just love. I could see getting it in more colors.
 
my small city bal serves my life so much, i have it in 4 colours
then for the times i need it but as shoulder bag, i have 2 firsts
then for bigger capacity, i have town, parttime and regular city.

oh, they are all in the variation of black and red only. and no, i dont think they are too many because there’s no other bag that can fill that void.

except ferragamo sofia, that i have 5 in different colours and sizes
 
If it works why break it? I used to have three Balenciaga Day bags in different colours. Eventually I kept only one but for a while I really enjoyed wearing them all. If you notice that you're not using one of them you can always sell it on... Enjoy your new bag, it's a beautiful colour!
 
I currently have 3 polene handbags in the un nano style, but in different colors. I have it in black lizzard, taupe, and trio camel. I really like the midnight blue color. But is 4 bags in the same style overkill? Would love to hear your thoughts.
If you've found a bag that really works for you, then 4 is not too many. You can switch up based on your mood or occasion. I say go for it!