All this talk of a FRR wall causing the rates to decline always strikes me as very silly. Why does the wall exist?  It is because there is excess supply due to swap rates being 2-10 times higher than the market rate, and due to friction costs of moving money in and out of Bitfinex.

I think the FRR wall isn't suppressing interest rates - in fact it is preventing them from falling fast enough to balance supply and demand. This was especially noticeable with the long decline from 0.1% to 0.04%. The 4 million FRR wall was a product of declining demand (due to the bear market), excessive supply,and a FRR rate that was too high.