Dropdown navigation not displaying past the header

[ManellyC]

This is happening on multiple sites. This is an example: ​https://www.mightyepiphyte.com/
Since the recent WordPress update the drop-down menu is no longer showing below the header.

[sabernhardt]

The header on your site has a Cover block, which ​clips or hides its overflow.

For a quick fix on that site, you could go to the Editor, open the Styles menu (half-light, half-dark circle icon), open that panel's 3-dot "More" menu, select "Additional CSS" and paste the following styles:

.wp-block-cover {
  overflow: visible;
}
.wp-block-navigation-submenu {
  background-color: #8cc63f;
}

(the submenu would need a background color)