diff '--color=auto' -ur qtwebengine-5.15.19.orig/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator.cc qtwebengine-5.15.19/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator.cc
--- qtwebengine-5.15.19.orig/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator.cc	2026-05-20 20:11:54.000000000 +0200
+++ qtwebengine-5.15.19/src/3rdparty/chromium/third_party/blink/renderer/platform/text/text_break_iterator.cc	2026-05-20 20:52:02.364330574 +0200
@@ -162,7 +162,9 @@
 };
 // clang-format on
 
-#if U_ICU_VERSION_MAJOR_NUM >= 74
+#if U_ICU_VERSION_MAJOR_NUM >= 78
+#define BA_LB_COUNT (U_LB_COUNT - 9)
+#elif U_ICU_VERSION_MAJOR_NUM >= 74
 #define BA_LB_COUNT (U_LB_COUNT - 8)
 #elif U_ICU_VERSION_MAJOR_NUM >= 58
 #define BA_LB_COUNT (U_LB_COUNT - 3)