I'm sure plenty of people here sell enough mods to owe some decent taxes on them, but slide under the radar because it's less than $20k. And fair enough, not judging. But the world is catching up to these business practices, in the typical slow way these things take, and you're going to end up paying your share now.
So it goes. As chuckwurt noted, you should have been already, so consider whatever you didn't a bonus.
As for cash ... I haven't withdrawn a chunk in a bit, I don't know if anything has changed in Pandemic Times™ but last time I went to my BofA and said "gimme $7k in bills" there wasn't any noise about advance notice, or "sorry sir, you need to drive to multiple branches". They gave me an envelope of $100s, I bought my Metallica LE.
Maybe that's my SoCal metropolis experience and more rural places can't hang with that, I dunno. It sounds frustrating though. It's your money, right? Too many rules about getting access to your own damn money sound wack to me. Sucks if you can't just take your business elsewhere.