Many years ago, I worked with a person that had an erratic Social Security benefit that related to his government pension and was more complicated than normal. He had worked for a school system for many years (no Social Security), but then he also had several years employment with the federal government (sorry don't remember whether FERS or CSRS). All the while, he had a side sole-prop. business under which he paid into the Social Security system for 30 - 35 years. He had gotten a refund of pension contributions from the federal government. I believe that refund was part of the problem. He did get a pension from the school system.
His benefits, like yours, kept being "adjusted". He had much of the paperwork - pay records, periods of employment, refund of pension documentation, school system pension award - with all of this, he did finally work through his Congressman's office to get it straightened out - was it right??? However, his SS benefit did stabilize and he is keeping this documentation just in case it ever comes back up again.
I am gonna say that this sort of situation is unusual and it is because of the [individualized] particulars involved.
I will assume that your benefits might have some [individualized] particulars - if that is true, the only way to reconcile is to try to secure the documentation and work with them or see if they have what you have submitted - I think what you might need is ONE knowledgeable person that can work through this with you - step by step. I know that might be hard now since many of the local offices are still closed.
I read the Reddit - Social Security discussion board and there seems to be some government (SSA) professionals over there - they might be able to help you more if you can give more of the details and describe any potential [individual] particular - in general; you are still anonymous.
Sorry, can't help more - hope you can get it worked out; I know it is frustrating.
Good Luck
It's Always Something . . . . Roseanna Roseannadanna