This only affects ATN being opened via Firefox. If I search for ImportExport NG, it only lists version 14.1.10, which is compatible with 128.0 - 140.*.

The most recent version however is 14.1.14, which is compatible with 140.0 - 144.*

If ATN is supposed to show the version for the current ESR (140.0) it should show 14.1.14

Apparently this only affects mail extension experiments, and not (API) web extensions