I bought one last week.
There are 2 slots for the RAM and it's not soldered.

Looks like QNAP didn't handle this one very well: https://www.reddit.com/r...

Although here in the product page says Max RAM 8GB, looks like for at least a year or two they have expandable ram slots again.

I am interested in buying one but i want to install 32GB, if its soldered, I will have to return it.

I don't think this is possible in advance.
I also bought this device recently and they were not(!) soldered on my variant. I think that the information about the soldered RAM is a safeguard on the part of the manufacturer. So you could well be lucky.
You can also try to return the device if it doesn't meet your requirements (right of return). However, you will have to reckon with a loss of return value.

You can insert some as shown in the instructions.

Runs great