See also WinSCP suddenly opens with two local panels with seemingly no option to open a connection to my server. What do I do?.

Related: Issue 2217 – Make it harder to mis-click "never show this again" checkboxes

WinSCP still displays Login dialog on startup. But it can now be turned off. Maybe you did inadvertently.
See Show Login dialog on startup and when the last session is closed:
https://winscp.net/eng/docs/ui_pref_window

When I first installed WinSCP years ago the Site Manager would automatically open on start up.
And I used and loved that behaviour until a few weeks.

Unfortunately this stopped working after an update or maybe due to a misconfiguration.
How can I get it back to have Site Manager open on startup.

If it does not work anymore I could live with having a shortcut to do it.

Thank you very much for this great software.
Cheers