I received UK Visa refusal due to deposits I made in my account just before taking bank statement. Need advice fro applying again [duplicate]

I received UK Visa refusal due to deposits I made in my account just before taking bank statement. Actually first 17 months from April 2018 until September 2019 I received salary in cash, 70125 SAR from which I saved liquid cash 12000 SAR which i deposited in bank. Since September 2019 my salary account was opened by the company, and this is the main refusal point mentioned by ECO. so all my savings which is hardly 10-12% of my net salary I deposited in bank. But I dint mention anything about it.

All my other documents stating my salary slip / traveling itinerary etc were accepted.

For new application : I got the letter from my employer that since when I was receiving my salary in cash. I also obtained the exit and reentry visa (as its mandatory in KSA for expat) which clearly sates my traveling period and reentry in KSA.

This evidence is enough to prove my case? What should be my cover letter?

Secondly fro example I have submitted 10 documents in my previous application and they raised red flag for two. In new application I will provide same 10 documents with more evidence to prove my case. So is their any chance they raise red flag about some other document from the 10 which I submitted before and now as well.