Google indexes 12 versions of your blog post — but if hreflang is wrong, it picks the wrong one for a Turkish searcher, sends them to English, they bounce, and your CTR plummets.
The rules that actually matter: (1) every alternate hreflang link must be reciprocal — if /tr/blog/X links to /en/blog/X, then /en/blog/X must link back to /tr/blog/X; missing reciprocity is the #1 cause of Google ignoring your hreflang entirely. (2) Always include an x-default pointing to the canonical English URL — covers searchers in locales you do not translate yet. (3) Hreflang values use ISO 639-1 + ISO 3166-1, never combinations Google does not recognize (e.g. 'gb' is invalid; use 'en-GB'). (4) The canonical tag and the hreflang for self must agree.
Baynoy generates the full hreflang map server-side in Next.js metadata. Every page outputs <link rel='alternate' hreflang='LL'> for all 12 locales plus x-default, with the canonical pointing at the current locale's URL. The sitemap.xml carries the same alternates in <xhtml:link> form so Bing and Yandex pick them up too.
Result: a Turkish user searching 'stablecoin nedir' gets /tr/blog/stablecoin-101 in the SERP, not /en/.