Probably referring to how quite a few e-ID and online banking sites require you to use Chrome or Safari, as the companies behind them don't test with eg. Firefox.

The Danish "MitID", for example, doesn't quite work right with how a lot of apps using it for authentication (the default Firefox settings probably strip something from the intent links the MitID login page uses) and Danish citizen service sites require Chrome for some things such as booking an appointment, iirc.