Edit: I got it fixed with enabling pixelart, still curious for an explanation though?
In the latest release of Phaser, 3.19.0, my spritesheets become blurry, while in 3.18.0 everything seems normal.
My configuration is nothing special, only the width, height, parent, scenes and disabling context menu are set. Since this doesn’t happen in 3.18.0, I think that it might be a bug.
If necessary, I can show more codes.