Firstly, what you think is more likely as far as the macroeconomic situation: inflation or deflation?
There is absolutely no chance of seeing global deflation short term, ignoring the money printing we experience a pretty rare economical situation when the economy needs to start, it wants to start and go back to normal, it is pushed with incentive but at the same time because of prolonged periods of shutdowns, a slowdown in activities and completely uneven break of supply chains around the world (for example the container situation) inflation will still be around for a while.
People want stuff, people still have the money to buy stuff but there is a shortage of it, until this clams down and an equilibrium happens again you won't be able to even dream of deflation. Some speculate we might see an artificial deflation period on annualized data compared to the park prices in May and June this year but it will be short-lived.
If the latter, will that cause a massive Bitcoin dump to unexpected lows?
Nobody has a clue what will happen, it's a crazy world, and one tweet right now moves the market more than economic reports, so probably what is normal won't happen. Many argue that deflation is good for gold as periods of deflation saw better returns in gold investment than periods of inflation but I doubt this will be the same for Bitcoin.
A slight downtrend at the news about the US entering deflation, maybe! A massive dump? No!