Just like your college degree / education cost you money, the "education" of doing your first BRRRR could come from overpaying, underestimating rehab costs, overestimating ARV, delays from weather, unforeseen problems, etc.To put it another way: it's not guaranteed income, especially as prices are rising and it's getting harder to find BRRRRs that actually make numbers work.Btw, another commonly misunderstood fact about BRRRR: most investors aren't using that to generate cash flow or profit today.  

Also, I would have some reserves of a few months mortgage payment set aside or a credit line (even a credit card) for unforeseen expenses that pop up.

Loan applicants may lose their job and the underwriting process may experience delays to further complicate transactions.Real estate attorneys should be prepared for unforeseen circumstances.

Some unforeseen issues could include plumbing and electrical if the house is really old and hasn't been updated at all.

This is a minor example, I have had reno's that have bloated 20k+ in budget due to unforeseen items, and that's my cost which means it would be on average 30K+ for anyone else.

With foreclosures paused, will a DIL also be stalled for an unforeseen amount of time?

With all that said, I believe by 2022 things should be back to "normal"  so long as some new unforeseen, unrepresented event doesn't occur.

What if you have a large unforeseen CapEx expense in the first few months of owning the home?

Additional, the two are so different, the only large take away is that you should prepared for the unexpected by having options and buying with a margin of safety in order to account for unforeseen occurrences like this. 

I personally keep 6 months of mortgage payment plus $5K for unforeseen capital expenses.