You had this option https://prnt.sc/1l0edlpt enabled and it caused the issue. We have our own option for this in Theme Options -> Speed Optimization – https://prnt.sc/1l0hgdh
Please, keep the Jetpack option off to prevent jumping of header because of logo needed time to load but while it loads it shows as a placeholder and that placeholder could be with another size dimensions than the real image.
