By way of background, the IRS is issuing stimulus checks/direct deposits to most US taxpayers who have an SSN. If your income was less than $75,000, you would get $1,200 and another $500 per dependent.
Interestingly enough, US citizens living overseas are eligible.

You can find more details here.

Part 1: It might not be a check

The first payments were in the form of physical checks (or direct deposit for those who had their direct deposit information on their 2018/2019 tax returns).

While they are still issuing physical stimulus checks, the federal government is sending 4 million “economic impact payments” in the form of prepaid debit cards. The IRS noted that individuals cannot specifically opt to receive the “EIP cards,” as they’re known, over a paper check. According to the Treasury Department, they are distributing the cards to individuals who don’t have their bank account information on file with the IRS. Also, to those whose tax returns were processed by the IRS service centers in Austin, Texas, and Andover, Mass. The first cards were mailed out last week.

Austin, Texas is the center which processes tax returns for American overseas. They might receive a debit card.

It can be a good thing for those whose ties to the US are so weak that they don’t have a US bank account to cask it to.

It also leads to confusion with some taxpayer discarding that envelope as spam. Here are the signs that that debit card is indeed the stimulus check money you’re been waiting for:
– It will arrive in a plain envelope from “Money Network Cardholder Services”
– The name Visa will appear on the front of the card
– The back of the card has the name of the issuing bank: MetaBank
– Information will explain that card is your EIP card

Part 2: “the check is in the mail”

Many countries experience an interruption or disruption of their postal system due to COVID-19. If you are waiting for your stimulus check and you live in one of these countries, postal disruptions might cause that delay.
The affected countries are listed on the USPS Service alert website.

Part 3: The IRS is here to help

The IRS has created a new hotline you can use if you are waiting on your economic impact payment.

You can call 1-800-919-9835 and get answers on the status of your payment. Also, they have automated services and are adding call-center representatives.