Can we I identify crypto-exchange (BTC) hot wallets? I am interested in understanding, how the large crypto-exchanges handle deposits and withdrawals of BTC. I am aware of some examples of ETH-related hot wallets which are rather easy to identify but it seems to me this is not the case for BTC. I tried the following:
- Deposit and Withdrawal funds from my trading wallet at different crypto-exchanges (poloniex, kraken and bitfinex)
- Trace back the initiator wallet of these transactions.

Seems like they are kind of using several in- and outputs to hide the actual flows. 

So my question: If I am interested in tracking (approximate) BTC-flows between the different crypto-exchanges, what would I have to do?
it really depends. Some exchanges have their addresses labeled in services like Blockchain.com and so on. I believe they share with them the Xpub so they can map all of them back to the exchange.

Not all exchanges have that. 

I've tried to do that once and gave up because the quality of the data available on which exchange controlling which addresses is really low. Additionally some exchanges (I don't know how many nor which) do these interexchange transactions using the Liquid side chain. Maybe some of the blockstream guys hanging around can illuminate my answer here

So, unless you have direct access to the exchanges' Xpub or some good data source on labels, it's really hard to do this type of analysis