Google Photos links are not valid without authentication, so if you are displaying a link, it will not work unless the person viewing your website (e.g. me) has been granted access to your photo.
There used to be a link earlier, but since the link was almost always dead I removed it.
but for a public album I should always have authentication, right?
anyway how can I build the link to the Google Photos album so that I can check?
There is no concept of a public album in Google Photos if I am not mistaken. It used to exist for Picasa a long time back, but Google has systematically removed all means to create one, including disabling albums made public via third-party APIs.
anyway how can I build the link to the Google Photos album so that I can check?
There is nothing in Photonic to let you do this (not without editing code, at least). But a simpler test is for you to open the link to any album directly from Google in Chrome’s Incognito mode.