Code signing confusion

[instrumentally]

So this is a question for Microsoft and Sectigo, right?

Lindersoft provides a secure doorway to some unknown page, which I (and I suspect others) would have no idea was not associated with Lindersoft. The doorway page is trust-provider.com, not Sectigo.

Look at the snapshot below. Why would I suddenly become aware that Lindersoft is not associated with the certificate purchase process when the Lindersoft logo/banner is prominent at the top of this doorway page, which when the user clicks "Next" results in an utter failure to proceed?