From some empirical testing, it looks like Across Lite crashes if any clue is longer than 505 characters, though other apps naturally work fine.
For better compatibility, we could truncate + ellipsize clues that are longer than this, and flag this in the unsupported features warning, when exporting to .puz. It may also make sense to have an option to turn this off, since not all apps have this problem; that said, I imagine if you're using an app other than Across Lite, I'd hope that it supports .jpz anyway, and the number of puzzles impacted by this should be relatively small (but non-zero).
From some empirical testing, it looks like Across Lite crashes if any clue is longer than 505 characters, though other apps naturally work fine.
For better compatibility, we could truncate + ellipsize clues that are longer than this, and flag this in the unsupported features warning, when exporting to .puz. It may also make sense to have an option to turn this off, since not all apps have this problem; that said, I imagine if you're using an app other than Across Lite, I'd hope that it supports .jpz anyway, and the number of puzzles impacted by this should be relatively small (but non-zero).
Example, for testing: https://craftycrosswords.blogspot.com/2022/12/radicalized-by-apush.html (ref: 23-Across)