There is no hard limit, but there is a point of diminishing returns.
- Five to fifteen specific tags is a good target.
- Each should be something a real person would type.
- Prefer specific over general: “qabuli palaw” beats “food”.
Fifty vague tags do not make you rank for fifty things; they make your listing look like spam at review.
A good set looks like this
For an Afghan restaurant: mantu, qabuli palaw, bolani, ashak, kebab, halal, takeaway, family friendly, halal meat, catering. Ten tags, every one a phrase somebody types.
A bad set looks like this
best, cheap, number one, food, restaurant, good, quality, service, near me, top. Ten tags, not one of which distinguishes you from anybody.
A wall of vague tags reads as spam at review and can delay publication.