Section 3.6 says that UI customizations such as language preferences are only exempt if they last for a session (no more than a few hours). Anything longer requires a cookie notice, though they do claim that a less prominent notice than a modal is acceptable.
Page 8 of the PDF[1]: 3.6 UI customization cookies
> These customization functionalities are thus explicitly enabled by the user of an information society service (e.g. by clicking on button or ticking a box) although in the absence of additional information the intention of the user could not be interpreted as a preference to remember that choice for longer than a browser session (or no more than a few additional hours). As such only session (or short term) cookies storing such information are exempted under CRITERION B.
It specifically says that a consent notice is required for UI customization cookies that persist more than a few hours, and it gives an example of preferred language as one of those UI customizations.
> Page 8 of the PDF[1]: 3.6 UI customization cookies
What's "Opinion 04/2012 on Cookie Consent Exemption" adopted on 2012, 4 years before GDPR?
Edit On top of that, actual quote:
--- start quote ---
"They may be session cookies or have a lifespan counted in weeks or months, depending on their purpose
... addition of additional information in a prominent location (e.g. “uses cookies” written next to the flag) would constitute sufficient information for valid
consent to remember the user’s preference for a longer duration,
--- end quote ---
12 years since this opinion, 8 years since GDPR, and you still have no idea about either.
