This was more of a case in the 90s, nowadays Latvia is more economically developed for this to be a huge concern. Even the population decrease at the moment is more due to the fact that way less people are born than die, not due to emigration of Latvians, as approx the same number of people arrive in Latvia as leave it. With Ukrainian refugees there has even been population increase this year so all these estimates may also change if there is more instability in the region in Russian speaking countries and we have more relaxed immigration policy (it has also been rather strict compared to say Poland, since we already have a big Russian speaking minority, like you cannot employ a Ukrainian or Belorussian or anyone for minimum wage in Latvia, you can only pay them above average wage and only if a Latvian is not applying for the same job, of course there are ways how to avoid this, usually they employ a dude in Poland or Lithuania where it is way more relaxed and then send them here as a contractor or sth like that, but it is more tricky)

Latvians can go to USA visa free without any engagement, well at least to travel. But if people leave Latvia for work, it is today mainly to other EU countries, no need to travel so far away from home for better salaries and also no need for work permits or green card. Also Norway, due to high salaries, and still UK, although maybe rules are more tight now.