From https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

Index: http.h
===================================================================
RCS file: /cvs/src/usr.sbin/httpd/http.h,v
diff -u -p -r1.16 http.h
--- http.h	12 Sep 2020 07:34:17 -0000	1.16
+++ http.h	23 Mar 2024 11:35:17 -0000
@@ -131,7 +131,8 @@ struct http_error {
 	{ 100,	"Continue" },				\
 	{ 101,	"Switching Protocols" },		\
 	{ 102,	"Processing" },				\
-	/* 103-199 unassigned */			\
+	{ 103,	"Early Hints" },			\
+	/* 104-199 unassigned */			\
 	{ 200,	"OK" },					\
 	{ 201,	"Created" },				\
 	{ 202,	"Accepted" },				\
@@ -175,10 +176,10 @@ struct http_error {
 	{ 418,	"I'm a teapot" },			\
 	/* 419-421 unassigned */			\
 	{ 420,	"Enhance Your Calm" },			\
-	{ 422,	"Unprocessable Entity" },		\
+	{ 422,	"Unprocessable Content" },		\
 	{ 423,	"Locked" },				\
 	{ 424,	"Failed Dependency" },			\
-	/* 425 unassigned */				\
+	{ 425,	"Too Early" },			\
 	{ 426,	"Upgrade Required" },			\
 	/* 427 unassigned */				\
 	{ 428,	"Precondition Required" },		\