There is a context missing in regard to why Mazars have a public concern about their proof of reserve reports to those companies. It is explained as follows:
Binance and many other crypto firms are privately held, meaning they dont regularly if ever release financial data. So the short-lived proof-of-reserves information was welcomed by the industry.
The now-withdrawn reports published by Binance and Crypto.com were often misunderstood as actual audits, that is unbiased examinations and evaluation of the financial statements of an organization. But theyre really just a matching exercise that involves mapping customer assets as recorded in an exchanges internal database to entries in a public blockchain, according to Francine McKenna, a lecturer in financial accounting at the Wharton School at the University of Pennsylvania.
proof of reserves mean very little without proof of liabilities,
As noted above, the reported Proof of Reserve is not a big picture, in fact, it can't be counted as a variable if someone wants to prove solvency.
Who is to say that funds cannot be shifted at any time, like SBF did from FTX to Alameda?
Any reports cannot guarantee that. It is the wrong thing to rely on.
Unfortunately, in a cryptocurrency world, handing over one possession to centralized entities is a sure way to make the funds can be shifted without their concern. Not your keys, not your coins. The problem in regard to the current FOMO of exchanges published their proof of reserve is that kind of framework is not enough to attest solvency of exchanges, as already noted above.