Can't say anything for Mouser, since never ordered from them, but, recently, digikey went nuts - I was ordering couple of Atmega168s and corresponding stuff, like crystals, sockets, etc. ($100 grand total)
So they sent me different forms to fill in, like who will be end user of these parts, why I need them, where they will be used, I agree that I will not send these parts to Iran and so on.
Feels like I was placing an online order for a nuclear warhead
Ok, I filled it all, scanned and sent them back, they shipped and everything is fine.
However, I found that I forgot some components and decided to place an order again.
They AGAIN sent me all that paperwork to fill, but my shipping address, billing and everything was exactly the same as in previous order.
When I asked them, why I need to do this all the time, they said - "this is the law"
So I gave up and now ordering parts from LCSC - while their inventory is not that good as digikey's, and atmega's are a bit expensive there, they have much more cheaper parts available and they do not ask silly questions, like digikey does.