themes-wordpress/quadrat/sass/templates/_footer.scss

.home {
	.site-footer-container .wp-block-group {
		&:before {
			content: "";
			background-color: var(--wp--custom--color--tertiary);
			clip-path: polygon(41vw 49vw, 100vw 68vw, 100vw 100vw, 18vw 100vw);
			position: absolute;
			height: 100vw;
			bottom: 0;
			left: 0;
			right: 0;
			z-index: -1;
		}
	}
}