Wow! Adobe will disable support for authoring with PostScript Type 1 fonts in January 2023. I'm surprised that I'd not heard about this sooner. When you consider that PostScript helped pay the bills for Adobe for years prior to Illustrator, Photoshop or any of its current cash-cows, this is big news.
As Adobe explains in their support note, the old Type 1 font file format has been on borrowed time for a long while now:
Type 1 fonts (also known as PostScript, PS1, T1, Adobe Type 1, Multiple Master, or MM) are a deprecated format within the font industry, replaced by the larger glyph sets and more robust technical possibilities of OpenType format fonts.
Type 1 fonts were introduced by Adobe in 1984 for use with its PostScript page description language, and became widely used with the spread of desktop publishing software and printers that could use PostScript. In 1996, Adobe products and type development began to concentrate on the use of more versatile OpenType fonts rather than Type 1.
While the use of Type 1 fonts is still supported by some operating systems, it is not supported in many environments crucial to modern platforms, including web browsers and mobile OSes. The lack of support for Unicode information in Type 1 fonts also limits their ability to support extended language character sets.
I've not encountered any Type 1 fonts in active use in over a decade now, and when I did a clear-out of old fonts from my Mac several years back, it was clear to see why. Not only were they lacking any Unicode support, but many gave themselves away by the lack of the Euro currency symbol, for instance.
For those with digital archive documents containing these older fonts, those should still be viewable, if I'm reading the support note correctly, since the font information is embedded into the document.
The headaches look to be reserved for those with artwork libraries, who are potentially looking at hefty bills to replace the old fonts with modern versions.