You're saying if I sell 1BTC on Bisq and I suddenly get $20,000 via bank transfer, which on other days doesn't happen too often, the bank is going to ask questions? I mean, you could just reply to those questions honestly and say you bought BTC at a certain earlier point in time and sold it online.
Not so simple if the money come from a complete stranger. But, if they come from a well-known, billion dollar worth of company, "the bell might not ring". Again, though, I'm not so sure what to do with the tax office.
I don't think it would be a big issue; it's going to be similar to buying (or selling) another expensive item like a car.
It isn't, because, first of all I can't evade the taxation of a mobile (in contrast with bitcoin), and second, there's normally a legal framework around that and I know what I should do, how much it'll cost me in the end etc.
but I believe most countries do have something by now
Unfortunately,
not.
In general I don't think using a centralized exchange to do something illegal in your country, is going to make it legal.
Me neither, but I have a feeling that people who use a centralized exchange cover up this issue. Maybe I need to reach an accountant.