subdomain vs url for multi language site ? which one is better based on your experience ?

i have multi language sites & currently using url format (site.com/de-DE/post-name), already ranking for multi language keywords but was wondering if it would be better to go with (de.site.com) instead? i have +20 languages, which one is better ?

Go with the currently format. It's more common.

There's no need to fix what isn't broken if you're already ranking well with the /de-DE/ structure. Google treats subfolders well for multilingual SEO, they are simpler to maintain, and they better consolidate domain authority. Without a good reason (such as separate teams or regional hosting), moving to subdomains like de.site.com could reduce link equity and increase overhead.