disable extension autoupdates?

[Admini]

amazing!
I removed the flag --cb-disable-extensions-auto-update and the extensions stopped updating,
this is my startup command line now:
[StartupCommandLine]
enabled=1
switches=--high-dpi-support=1 --force-device-scale-factor=1.0 --renderer-process-limit=3 --media-cache-size=0 --disable-preconnect --dns-prefetch-disable --no-pings --cb-disable-user-statistics

This means "--cb-disable-extensions-auto-update" worked as "--cb-enable-extensions-auto-update" in fact.
But it is not possible according to our investigation.