Not in the last 90 days, as far as DATEV's changelog and our daily checks show.
How often does the DATEV API change?
We have too little history on DATEV yet to say.
Where is the official DATEV API changelog?
DATEV publishes it at https://developer.datev.de/datev/platform/en/node/35016. This page follows it daily and dates each entry.
How do I get notified about DATEV API changes?
Subscribe to this page's RSS feed (https://seamless.engineering/api-changelog/datev/rss.xml). If you would rather have someone act on them, we operate DATEV integrations and handle changes like these before they reach production.
We watch DATEV because we run integrations on it. If one of yours depends on DATEV, we can take it over: build it properly, operate it, and fix it when DATEV changes, before your data is affected. Fixed-price scoping quote within 48 hours.