Hey Adam, Apologize for the delayed response first of all. Coming to your question… as far as I have been able to understand, it’s not just the new BTC supply coming into the market but the existing ones sitting in the cold storage as well which were brought back to life with a move to the wallets. At the time cryptos were bottoming, investors were happily holding on to their coins in a storage, but when the market began to recover at the beginning of the year, they became active again.
Secondly, I think it is just the study for the past 6 months since the bottom. Diar didn’t mention anything about the other exchanges doing the same as Coinbase, but the trend is one of moving from exchanges to independent wallets — with a build of investor interest & a fear exchanges being hacked. I don’t know if I made any sense to you but hope it helped.