Fonts are not Type 1 PostScript
This check flags up when Adobe PostScript Type 1 fonts are used in the InDesign document.
PostScript Type 1 fonts, as their name suggests, were intended for print production using Adobe PostScript. They are an old font format which have largely been superseded by the later OpenType format as PostScript Type 1 fonts are not supported in digital and web publishing.
Adobe announced they were stopping supporting PostScript Type 1 fonts in any new software released after 2021.
Note that Type 1 fonts will no longer appear in InDesign's Font menus and must instead be replaced using Type > Find/Replace Font:
PostScript Type 1 fonts show their Type as ‘Type 1’ and warning signs alongside their name in Find/Replace Font’s dialog.
Fix this problem by finding and activating a different font format in InDesign or in some cases by substituting for other fonts.
