When the ITK logo was updated as part of the discussion Updated ITK Logo, its usage on the website, including the defined favicon, was updated, but not the “Apple Touch Icon” (see definition). For the longest time I have noticed that the icon used as part of favorites/recents in Safari on iOS was the old ITK logo.
The discourse source shows that the new icon is defined, but the apple-touch-icon is still being defined as the old logo.
<link rel="icon" type="image/png" href="https://discourse.itk.org/uploads/default/optimized/1X/71db04d41479c229accbe8bf0b99195f75f46770_2_32x32.png"> <link rel="apple-touch-icon" type="image/png" href="https://discourse.itk.org/uploads/default/optimized/1X/446cf4a415241d375dd075571f07c0ce79c703af_2_180x180.png">
Also, https://itk.org doesn’t define an “Apple Touch Icon” so it just uses the letter “I” in Safari favorites and it uses a screenshot of the webpage as the icon when adding to the Home Screen.