How bad does it look if my PI writes a generic letter?

My PI just said he will write me a generic letter. I was the first author on a paper I wrote under him that got accepted into a top journal in my field(the acceptance rate is kinda high though). I was really banking on him giving me a really strong letter. How bad does it look if my PI writes a generic letter? I think I will get atleast one strong letter from my other PI and a generic letter from one other lecturer.

My academic stats are mediocre tbh but I believed my edge was in research experience. Now I am not sure.