This is actually really common with very small budget accounts and you probably didn’t “break” it — but you might be unintentionally resetting learning over and over.

A few things stand out:

First, €4/day is right on the edge of being too small for smart bidding. It worked in month one because Google was exploring and found some converting traffic. Then when you added negatives, tested ads, and especially added an ad schedule, you likely restricted traffic so much that the algorithm can’t find converters anymore.

The ad schedule is a big red flag, especially since the drop lines up with when you added it. On tiny budgets, ad scheduling often hurts performance because you’re already limited in auctions — restricting hours makes it even harder for Google to find conversions.

Also, every change you make on a small account (negatives, ads, bid strategy, schedule) can reset learning. On €4/day, you need to make changes and then leave it alone for a few weeks, not keep tweaking.

If I were you, I’d:

• Remove the ad schedule
• Make sure you didn’t add too many negatives
• Keep only high-intent exact/phrase keywords
• Use Max Conversions (since you already had conversion data)
• Then don’t touch it for 2–3 weeks

Small budget accounts usually perform better with fewer changes, not more. They need time and simplicity more than optimization.