We already have a fair amount of advice on this, in our question How to show MIT license on icons, but you've indicated you'd like a little more detail on what text to preserve. If you go for the "link to a licence page" option, that link should appear on every page that contains the icons (or better still, every page of your site), and the page itself should contain the licence text, as well as all upstream copyright notices (which will likely be of the form
(c) 2020-2022 Fred Developer).
You've also indicated a preference for the "link to a licence page" option since you're not confident that the icon metadata will be preserved on deployment. Given that the licence obligations are yours to fulfil, if you're not sure of that, then a licence page is an acceptable way to go.