That's right, this key(for Darksiders 3) can be activated in the following countries
Argentina,
Armenia,
Azerbaijan,
Bahamas,
Belarus,
Belize,
Bolivia,
Brazil,
Chile,
China,
Colombia,
Costa Rica,
Ecuador,
El Salvador,
French Guiana,
Georgia,
Guatemala,
Guyana,
Honduras,
India,
Indonesia,
Kazakhstan,
Kyrgyzstan,
Malaysia,
Mexico,
Nicaragua,
Panama,
Paraguay,
Peru,
Philippines,
Republic of Moldova,
Russian Federation,
Suriname,
Taiwan,
Tajikistan,
Thailand
Turkey,
Turkmenistan,
Ukraine,
Uruguay,
Uzbekistan,
Venezuela,
VietNam,

The package say like this:

This package is only purchasable in specified countries
Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Russian Federation, Tajikistan, Turkmenistan, Uzbekistan, Ukraine, China, India, Bahamas, Panama, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Venezuela, Colombia, Guyana, Suriname, French Guiana, Brazil, Peru, Bolivia, Paraguay, Uruguay, Argentina, Chile, Ecuador, Mexico, Turkey, Taiwan, Philippines, Malaysia, Indonesia, Viet Nam, Thailand

Yes and no (some countries are, some aren't), plus each publisher defines their own idea of "LATAM".
Better check on SteamDB the countries that receive a region-locked key (you have the subs linked in the OP). For example, customers from these countries will receive a region locked key for Imperator: Rome:

Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Russian Federation, Tajikistan, Turkmenistan, Uzbekistan, Ukraine, Bahamas, Panama, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Venezuela, Colombia, Guyana, Suriname, French Guiana, Brazil, Peru, Bolivia, Paraguay, Uruguay, Argentina, Chile, Ecuador, Republic of Korea, China, Turkey

Which country are you interested in and for which game?

If it's two keys, it'll be two entries in the chart too.

The price. And I tried to cancel and and it gave me a $4 discount, so that's something worth trying every month. I now got this month for $8.

True, just cancel it, not worth anymore.

Tbh, it seems like all of them are marketing tricks. Classic plan just puts extra pressure on people before they cancel it, knowing they won't be able to get it back, whatever we are losing is questionable tho maybe freedom to pause a month or assurance to always get the best bundle deal in case they decide not to give 12 games to everyone some day.

You can't. It's not listed as such on the bundle page, nor on your purchase page but the key delivered for all regions is the deluxe edition (one key).

Hi, would you be able to provide a sub id?
There is no package strictly locked to SEA on SteamDB (neither for the other versions of the game), and there are some SEA countries (a few only) in the package shared between countries from a low-priced region (the one mentioned in the OP), but I didn't include "SEA" in that category simply because the package title "Darksiders III (LATAM/RU/CN/IN/TR)" doesn't include it either (maybe because they restrict it for only a very few countries of SEA) - is that what you mean?

Yes, that is how it is these days. Unless you were a subscriber before the change and kept what they call the "classic" subscription. More info on that here: https://support.humblebundle.com/hc/en-us/articles/360036658733

With premium you get to keep all 12 games tho, it's a service they've been giving for the last three or four months now, nobody knows for how long it will last.

They regularly have promotional offers that are not as absurdly priced.
It's all marketing tricks and hoops in the end.

even d3 at the price with coiupon is worth solo. Lower steam for me was 57zl, when for bmonthly im paying around 48+i got 11 more games, can sell cards from them etc

The package that the key activates is not sold on the store; however the sub needs to be listed there so that the table row is properly colored for RaChart users.
Because the link doesn't go anywhere, there is another link (a working one) in the first column to the right, it corresponds to the store bundle that contains the same items but it is NOT what you get from November 2020 Humble Choice.

Hi, please check this comment.

Yeah this is amazing, assuming you are on classic. No idea what they're doing what all those deals for newcomers.