On iOS 14.5+ the logo image in some cases may have an incorrect height ~ 33k pixels when using the CSS property height:auto. This causes the logo not to be displayed properly in Piano templates.
In order to fix this, you would need to limit the height of the logo image by adding a max-height property to the CSS styles of your website. For example like this:
/* Mobile */
@media (max-width: 479px) {
.pn-widget__logo {
margin: 0.5rem auto;
display: block;
max-height: 31px; // add this line <------
}
...
}