How do I know which app or program on my MacBook is using Legacy System Extension?

Concerning Apple’s announcement regarding Legacy System Extensions, there is nothing we have to do or be worried about at this time. What Apple is telling us is that when the next new operating system comes out (Big Sur), it will no longer allow those Legacy System Extensions which are part of other vendor’s apps. That means that any software vendors who have failed to update their offerings will be incompatible with the new OS. Those vendors have all been told what changes they will need to make to be compatible and I assume they are doing so. The bottom line is this. Before installing the next OS we need to visit our vendor web sites to verify that they have updated their offerings. If an important software has not been upgraded, then it might be a good idea to wait before installing Big Sur. Some people ask why Apple does not identify what programs use these extensions. This is because sometimes more than one vendor may use the same extension. In the meantime, it is nothing we need to worry about.

I think Apple did a very poor job of explaining this. But hopefully they handle it better once it happens.

You should always wait a few iterations of a new OS to get the bugs worked out, that's likely a year from now!

No need to worry, but to see them, just don't upgrade to 10.16 or iOSXi, or whatever Big Sur is if the developers don't have updates...

About this Mac>System Report>Software>Extensions, click on Obtained from Header, all that aren't Apple are Legacy.