diff --git a/changelog.d/7048.doc b/changelog.d/7048.doc
new file mode 100644
index 000000000..c9666f333
--- /dev/null
+++ b/changelog.d/7048.doc
@@ -0,0 +1 @@
+Document that the fallback auth endpoints must be routed to the same worker node as the register endpoints.
diff --git a/docs/workers.md b/docs/workers.md
index 0d84a5895..cf460283d 100644
--- a/docs/workers.md
+++ b/docs/workers.md
@@ -273,6 +273,7 @@ Additionally, the following REST endpoints can be handled, but all requests must
 be routed to the same instance:
 
     ^/_matrix/client/(r0|unstable)/register$
+    ^/_matrix/client/(r0|unstable)/auth/.*/fallback/web$
 
 Pagination requests can also be handled, but all requests with the same path
 room must be routed to the same instance. Additionally, care must be taken to