Did Catch rates decrease after Gen 4 update?

I don't want to add fuel to the no catch fire, but regular pokeballs don't seem to cut it for me anymore. I've been either berrying every mon or stopping every so often to ditch the red weight

There seems to be a lot "undocumented" tuning going on in Pokemon go. Sometimes good, sometimes not so much.
Some examples:
- Spin and raid rewards. Small amounts of tuning can make big differences.
- Shiny rate. At least in the beginning, the first hours of a new shiny release had much higher rates than later. You could get ten or more shiny in an hour the first hours, and then just an occasional rare one after that. Probably to get the interest up.
- Rarity, also inbetween events the relative rarity may vary a lot. A bit harder to track now when it interferes with weather boost.
- The ever changing boxes, a couple of main themes would have been enough, now it is usually a rollercoaster ride in "worth".
etc, etc.

If there is a tuning in catch rate it might be related to an effort to decrease Go+/Gotcha play. Many research tasks are in that line. Hard to tell at the moment. But there is no doubt that the game is constantly tuned back and forth.

1) It's probably "R"NG.

2) You're not the only one. I've been noticing this for a few weeks now (ever since I got the update); during the Halloween event, I even had two Level 1 Shuppets jump out after being hit with a Curveball with a Red ball - something I thought was effectively impossible. Yet it happened to me twice.

I'm also getting spurts where it's like I'm soft-banned - 5-10 minutes at a time where every Pokémon jumps out and flee's after the first ball (neither of the Level 1 Shuppets were caught during these times; I caught them on the second ball), where spinning Pokestops doesn't work for no apparent reason (no error message, plenty of room in the bag, not going above the speed limit, etc.). Then it's all back to normal, no issues.

Other people I raid with have notice similar issues, but not all of them - even the people I raid with who I "know" spoof (I can't prove it, but I know they spoof on occasion when they post that they're coming to a raid but only show up in the raid itself, and we don't see them in person. Generally we look the other way for them because they aren't abusing Gyms or doing anything that affects other players negatively.) aren't having these issues en masse.

So I'm pretty sure that this is some tweak to the "R"NG, not an actual change to the Catch Rates in general. There's a good thing to this, however - I know how to fix it!

Find the "Three Excellent Throws in a Row" Task.

Once you get that Research Task, you'll be back to catching every Pokémon with 1 Red ball, regardless of Berries or Curveballs or Bonus. Find a Level 35 Charizard? No problem! 1 Red Ball. Do a Giratina Raid, get 2 Excellent Curveballs in a row and catch it on the second one.

(I'm only partially joking here; I had the 3 Excellent Curveballs in a Row quest for almost the entire Halloween event, and I caught all but 1 Giratina after 2 straight Excellent curveballs. And none of the First Ball Jumping issues happened at all while I had the quest - even when I WANTED them to jump, like a wild Onyx (that turned out to be level 24). ARGH! Niantic, why do you do this to us?)