Ok, so the basic brewing process is this (not homebrewing detail here, just a distant overview):
Heat your wort with water, steep, then add hops and boil, add more hops as you begin to cool, once cool enough add yeast, ferment, bottle.
Flavored beers can be made a bunch of different ways. You can add herbs, spices, or flavorings before or after the boil, for example. Seeds and roots would usually be added before the boil; herbs would usually be added after. I would probably add fruit after but this is something that folks could argue about forever. If you buy something like smoke-flavored beer, chili flavored beer, etc. these are probably made this way.
There's a second type of flavored beer I have seen for sale in certain bars and restaurants in Asia though. That's where you take a fairly light beer on tap and add it to a glass along with a shot of flavoring syrup (like lychee or peach). These usually have sweeter flavor with clearer fruit flavors than the fermented fruit beers. If the beer is pasteurized, the flavoring could be added before bottling and carbonation. I think that is what you are seeing.