Short answer
Yes, giving it daily is a bad idea. Vanilla extract is mostly alcohol, so repeated small amounts can add up and cause alcohol poisoning over time. The safest approach is to avoid it altogether or use a tiny drop of pure vanilla bean instead. Watch for any signs of lethargy or wobbliness, and stop giving it immediately if you notice them.
Vanilla extract — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
Vanilla itself is fine, but extract is mostly alcohol. Use only a drop, or use vanilla bean.
The full verdict, portion guidance and serving notes are collected on the Vanilla extract food facts page.