It's one that I use in my works often, along with other people's aswell. It's basically Superflat Pop, Vectorgarden, Y2K and Frutiger Metro (amongst other aesthetics) thrown into a blender, but mostly a simplified Vectorgarden type of one. It would've existed in the mid-late 90s to late 2000s. Common visuals include colourful graphics (mostly pink and green), flowers (mainly "blob" like ones), overlapping circles and other geometric sort of things. I made a board on Pinterest about it (the first image is actually one of my own works): https://www.pinterest.co.uk/LovelyAnimations/simplified-vectorgardensuperflat-pop/