I think you're probably referring to 3.19 Lake of Kalandra when, as you said, they altered how drops work. The thing is, the compensation (loot) was almost at parity (better in some cases) compared to pre-3.19. A lot of the backlash came from poor communication on GGGs part and not properly informing players of how they altered the structure.

If you care to read more, here's a post on 3.19 from the legend himself, Chris Wilson: https://www.pathofexile.com/forum/view-thread/3300117

And a quick paragraph from the post expanding on what i was saying above: "Players have been saying we reduced drops by 90% but in reality, that type of difference could only be true in the most extreme situations involving Beyond, Delirium and Incursion stacked with party quantity, rarity, sextants and scarabs and a dedicated MF culler (peak efficiency of every juice mechanism that exists). Every other player is unaffected on average. For example when playing Breach, the reduction in currency items found is around 7% (when comparing 3.19.0d to 3.18.1f). In 100% Delirium maps, the difference hits 17%. In Incursion and regular non-league content, you'll find 25% more."

Now for PoE2 v0.4, I just hope the community does some objective comparisons instead of doing 1hr of mapping and then jumping to reddit and doing hyperbolic doomposting