Nav bar shrinks and then goes to correct height after a few seconds. HELP

Site URL: https://www.rollingpictures.ca

I didn't notice it before but my nav bar does not load smoothly. In addition to that it starts off at a smaller height, and then increase to what the height should actually be (which is not ideal).

I ran a third party speed and performance analysis and it states that "image elements do not have explicit width and height". I'm guessing that this is the problem but how do I solve it?

The video attached shows what happens with the nav bar (don't worry about the very minimized video - it's because I removed all my css code to make sure that it wasn't affecting the navigation - which it doesn't seem to be).

Screen Recording 2021-05-21 at 11.57.49 PM.mov