@Jovana I can confirm that this solution works perfectly now. 
The steps to embed infinity in Notion.
1. Make your board public with a unique password.
2. Embed board in notion.
A] - If you are also logged into infinity in your browser, this will just work everywhere without a password prompt.
-This is brilliant and exactly what I wanted, now everything works again. Thanks! this is a great solution for an infinity owner to work inside Notion.
B] - If you are not logged into Infinity in the browser, each individual embedded board will show a popup asking for the board password. This will be valid until refreshing or closing the page.
- This is brilliant! If I need to share a Notion page with someone publicly they can see the notion page without access to the board showing a password prompt, but I can give them the board-specific password to enter, which will enable the view for them.
I have not tried elsewhere like in a website, but I assume it will be the same for other embeds.
Good work Infinity! 
Now we just need similar notes functionality to be built into infinity to replace the need for notion.
because obviously we are never satisfied as users and always want more.
Actually, I am hugely satisfied with this.
Thanks, team