The message says:
"A simulator update has been applied, please run GSX Level 2 Control Panel, and click the Disable Default Jetways button"
Which means, you should just do that, as the message says.
Fact you don't own or use GSX L2, doesn't mean you don't have the GSX Level 2 Control Panel since when you install GSX, you ALSO get GSX Level 2, just in Trial unless purchased so, it's completely working, in all its features, just only on the FSDT airports and on the 3 Trial airports.
