Gifski uses the png-quant library, and I wonder how this compares?
(I guess APNG is supported in many browsers, but uploading one often results in deleterious resizing/recompressing operations that ruins the animation. Discord uses APNG and webp for stickers afaik)
pngquant was a big comparison subject during development (it's a brilliant piece of work, and a mature tool that does a few things more than just quantizing). Take it with a grain of salt of course, but in terms of raw quantization performance, patolette had the edge, particularly when dealing with images with tricky color distributions. With that said, pngquant's dithering algorithm is way more sophisticated (and animation aware, I think). In fact, one thing where it really shines is that it spots with pretty good precision where adding noise would actually hurt instead of helping.
Another thing is that patolette can quantize to both high and lower color counts (the latter particularly with CIELuv), whereas pngquant is more well suited for high color counts.
Still, color quantization is a really interesting rabbit hole to go down if you're new to graphics programming, or at least it was for me. It's a mixed blessing that almost nobody has to confront the problem anymore.
Colour quantisation is still one of the best lossy image compression formats for when you have almost no memory or CPU.