[2021] getting back into the division 2. where can I find what changed?

I haven't played since the game released way back then. I remembered things like you can't build skill effectively without investing heavily, lower level mods being more useful than level 30 ones, and Liberty, the only exotic I managed to get, had 3 different talents or whatever.

now, trying to find any info gives me outdated information, so I don't know what to do or what's changed, what's safe to dismantle/sell, etc.

I have several questions but I don't know what they are yet since, I don't know what I don't know.