The artifacts may be exaggerated there, as that image got JPEG compressed twice - once by me, and then Imgur did it again and made it smaller (edit: actually, can't see a difference). Here, I've uploaded it as a PNG, so I don't think Imgur messed with it https://i.imgur.com/uzlR3Fj.png

WEBP can do better (uploaded as PNG): https://i.imgur.com/w8XnHda.png