add note that spoof_source_address is unavailable, refs #4914

docs/src/content/howto-transparent.md

@@ -278,6 +278,11 @@ sudo -u nobody mitmproxy --mode transparent --showhost
 
 ## "Full" transparent mode on Linux
 
+{{% note %}}
+This feature is currently unavailable in mitmproxy 7 and above
+(<a href="https://github.com/mitmproxy/mitmproxy/discussions/4914">#4914</a>).
+{{% /note %}}
+
 By default mitmproxy will use its own local IP address for its server-side
 connections. In case this isn't desired, the --spoof-source-address argument can
 be used to use the client's IP address for server-side connections. The

mitmproxy/utils/arg_check.py

@@ -16,7 +16,6 @@ DEPRECATED = """
 --no-http2-priority
 --no-websocket
 --websocket
---spoof-source-address
 --upstream-bind-address
 --ciphers-client
 --ciphers-server