Index: trunk/src/org/openstreetmap/josm/data/validation/tests/TagChecker.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/validation/tests/TagChecker.java	(revision 18819)
+++ trunk/src/org/openstreetmap/josm/data/validation/tests/TagChecker.java	(revision 18820)
@@ -500,4 +500,5 @@
             || c == 0x0273 || c == 0x019E // "ŋ/Ŋ" (U+0273/U+019E), see #18740
             || c == 0x0142 || c == 0x0294 // see #20754
+            || c == 0x1DBB || c == 0x02B7 // "ᶻ/ʷ" (U+1DBB/U+02B7), see #23138. Both characters are used in Lushootseed paired with a letter
             || (key.endsWith("ref") && 0x1D2C <= c && c <= 0x1D42); // allow uppercase superscript latin characters in *ref tags
     }