fonts and icons are definitely better, but some icons and fonts are not easy to get, so you can use Sprite. Look at the project requirements and don't stick to the choice

based on the above answer, go on to say
for the Taobao and Tmall you mentioned, most of them are e-commerce websites. At present, they have used more font icons.
in addition to font icons, there are SVG icons
example: Ali Icon Library

in response to your question, I have specially looked through these sites
JD.com still has a lot of materials and sprite pictures used by ICON

https://img.codeshelper.com/upload/img/2021/04/03/ddqjqluxy1e15186.png
https://img.codeshelper.com/upload/img/2021/04/03/fywiojbm3bg15187.png

but the problem is that we don't have to follow in the footsteps of big manufacturers
first of all, you need to know what the benefits of sprite are
, and then whether you need to use
in your project, because sprite is not just part of ICON

I am the front end I like font icons if it is icon
if you are doing H5 animation, then you can only use sprite

each has its own advantages, and each has its own most suitable scenarios. For example, you can't do excessive animation if you use font icons, but it's easy to use sprite, and it's easy to do it with css3's animation,.
for example, the animation I did in my article can only use sprite images.

each has its own advantages, but the sprite image used in rem layout is difficult to calculate, and another point is the defect of using the picture. The picture may be blurred at high resolution. The shortcomings of using font files are also obvious, for example, the support of multicolor icons is not perfect, if you need colorful icon, font files are not appropriate. Depending on the situation, choose a sprite image, a font file or a single picture. There is no saying which is the best, only which way is more suitable for your project.
it is recommended that you take a look at the application of Iconfont multicolor icons and gradient icons