quote from umberto from a simliar question in a earlier thread post
If you have only MSFS 2024, the FSDT Installer will automatically disable all GSX replacement jetway files, because they are not compatible with MSFS 2024 so, if you have only MSFS 2024 installed, check again if they have been in fact Disabled and if they haven't, put all jetway replacement files and all airport service files on the Disabled side and select Apply.
If you have both MSFS 2020 and MSFS 2024, you will be ASKED if you want to disable jetways and airport services, because doing this will affect both simulators. But it's not if you have any choice: if you use MSFS 2024, you must disable them all.
Those files are the only possible reason why GSX might affect jetways.
Another reason why jetways don't work, which doesn't have anything to do with GSX, is the presence of an Helipad nearby. There's a known bug (which dates MSFS 2020 and hasn't been fixed in 2024) that helipads close to a terminal will prevent jetways to work. The only solution is to edit the airport and explicitly disable the helipad.