JSS dropped for eerie reason.

[#1]

Hey, I know the tittle is a little weird. But let me explain the situation more broadly... Just a couple days ago one client sent me a direct offer and also some requirements for his project. But I am not crazy to accept a project I know nothing about from somebody I know nothing about. 

We exchanged a couple messages I went to sleep and saw he withdraw his offer, supposedly alleging "closed the offer because Freelancer didn't respond" (or something along those lines).

For my surprise, my JSS dropped from 100% to 89%, which made me outraged, it went straight down ten points cause of someone else's attitude, and I am completely sure that caused it since the JSS dropped immediately in an unusual date.

How can I avoid this ever in the future? It damaged me hugely, I losted my badge.

... Or I Will I have to just accept that cause Upwork's always gonna favor clients? 

[#2]

Here is how JSS is calculated.

https://support.upwork.com/hc/en-us/articles/211068358-Job-Success-Score

Nothing to do with the situation you described. 

[#3]

Hey Carlos, 
I don't know for sure, but as per other comments by experts here, - Withdrawn offers do not impact your JSS. 
Since you were never officially in a contract, nothing they say or do will really impact your profile.

Now, JSS takes time to update - usually a few days - So, it's most likely due to another contract
Here's **some** potential reasons:
- A previous less 5 stars review
- Even if a previous client left you a glorious public review, maybe they gave you an "okay" private review
- If a contract was closed (after you accepted the offer) without payments
- If too many contracts were closed around the same time

Either way, it happens to the best of us, Carlos. I understand how frustrating a dropping JSS can be, and it's worse when you don't know the reason. 
You'll get through it. Good luck!

To Other experts in this community - Please feel free to correct me if I've gotten anything wrong.

[#4]

- If too many contracts were closed around the same time 

That is not the case, but the other reasons are correct.