Fake samsung battery

I was making a battery pack with
Samsung INR18650-35E, I was short of batteries. are not available anywhere. My supplier had them refurbished. I bought this one, there appear to be two dots on the contact points. Spot weld that were not good and this was refurbished. I contacted the supplier and asked if I could spot weld them again? They said no, I asked why this was not mentioned in the information. Their answer that I can do whatever I want with the batteries. Weird answer, I just sent them back.
I bought cells from aliexpress, looked identical to samsung INR18650-35E. I bought these, afterwards I found information that they were deah.
Received them, they have printed Samsung on them.
I measured the voltage and immediately noticed that the voltage of this one was different from samsung cells. I also measure big difference in voltage 3.9V most but also quite some 3.8V.
A few questions:
The refurbished one with two dots, would it still be usable for spot welding? Light sanding from contact? Better use this one than the fake deah?
The Samsung 3.5V can I put these cells together with the deah 3.8V cells, is this taken care of by the bms when charging?
Should I test the deah cells before putting them together?

You should test, balance, and match, ALL cells,.....before assembling a pack.

if you have an IR tester, that would be a quick way of doing a quick test to see if they are good. So you don't waste your time. The IR on all the cells should be very close to each other.