OPNsense 22.7: interface is disabled due to unsupported sfp on a 10G port, and the Linux ixgbe tunable does not apply

After upgrading OPNsense from the 21.x series to 22.7 a 10G SFP+ port stopped working with interface is disabled due to unsupported sfp; the newer Intel driver actively disables unrecognised modules. The poster tried to set ixgbe.allow_unsupported_sfp=1 as a system tunable, which was not accepted. Hardware involved: Intel X520/X550 class (ix driver), third-party SFP+.

• Hardware: Intel X520/X550 class (ix driver)
• Transceivers: third-party SFP+
• Form factor: SFP+

Symptoms / messages:

interface is disabled due to unsupported sfp