They are incompatible with musl's iconv implementation relying on
encodings that are not supported by musl libc et cetera.

diff -upr csv10.0.0.orig/mats/io.ms csv10.0.0/mats/io.ms
--- csv10.0.0.orig/mats/io.ms	2024-04-13 15:51:20.280352351 +0200
+++ csv10.0.0/mats/io.ms	2024-04-13 15:51:46.850399748 +0200
@@ -534,9 +534,7 @@
      1)
  )
 
-(if (case (machine-type)
-     [(pb tpb) #t]
-     [else (embedded?)])
+(if #t
     (mat iconv-codec
       (error? (errorf 'iconv-codec "-73 is not a string"))
       (error? (errorf 'transcoded-port "unsupported encoding almost certainly bogus"))