Webflow provides hreflang specifications for localized pages in its automatically generated sitemap but only from the primary language’s URLs.
This is technically incorrect as the hreflang specification will not be parsed like the traditional <loc> items.
The result is that localized pages are effectively missing from the automatically generated sitemap, leading to slowing indexing of these pages as they have to be discovered upon crawl of a page with that specific hreflang relation.
According to Google’s own documentation for localized websites, each page (localized pages included) should be accessible in the sitemap or a separate localized sitemap. This issue could therefore be resolved by either:
Providing separate sitemaps for each locale (e.g. www.example.com/en/sitemap.xml or www.example.com/en-sitemap.xml).
Including the localized pages on the primary sitemap.