This is an accepted solution.
Cactus, limit is 250 tags per product.
Yes @Mad_Wizard 250 tags per product correct, but:
- how many unique tags in the whole store?
- how many tags in total for the whole store?
I am automating a store with 30k product_ids related each other with 5k series_ids so to return related products in a section I approached to grouping tags but you can feel some limits at the link below