To preface things, I have no proof that there was another shadow nerf to the odds of lower * boxes. However, I'm an avid fanatic of filling 3 weapons slots with 0* punch guns as well as my shield slot with iron bucklers in T2 therefore I can tell that the average amount of boxes went down to nigh nothing (I'm talking 1 box in ~300 heating attempts the past week).
It could just be a hiccup with my luck which has nothing to do with it.
If there was another shadow nerf to the odds of those boxes... I just want to know why? I understand that GH might want to encourage people to use Punch for UVs instead of abusing an updated system, but it just makes no sense to me.
An average player will need 2.5-3.5 vana runs to get a 1 UV pull at punch to most likely end up with a very bad UV anyway discouraging further engagement with that system. Being able to fill the, otherwise unused, gear slots with low * gear to gamble for boxes felt like having a nice alternative to saving millions of CR to outright buy a good UV'd piece of gear. The boxes aren't free either, there is a small input cost (negligible, but there still is one).
To provide some personal data, I've spent around 70-80 1 UV tickets I got from boxes since the forge update came out as well as around 10 2 UV tickets. The only good UV I got was a single CTR VH on one of my bombs, everything else was damage VS monster families with another single exception being CTR med on my iron slug.
It could be you merely had a downturn of luck. It could be the rates were changed behind your back. It could be there's a hidden cooldown on how many boxes you can get in a short timeframe, or you should've rolled for boxes while the invisible pink elephants were asleep so they couldn't intercept them, or some other hidden mechanic like how lockboxes drop from the Prize Wheel more often if you've been opening them.
The lack of transparency means all you have to go by are A) you're getting less boxes than usual, B) there were some behind the scenes improvements mentioned in a variety of patches heretofore, and C) a dev (Gyre-Of-Guile) was dismissive and smug about this when addressing negative feedback about the Slime Casino changes and hidden rates [https://forums.spiralknights.com/en/node/125014]. Even if you can't know concretely, that's still more than enough to be suspicious something could be different. You cannot trust that nothing changed just because nothing was explicitly listed.
I think that's emblematic of how poor communication is right now, where either things really are the same and you're left paranoid that it isn't, or something's different and you would only be able to find out for sure through massive-scale trial and error with something that already had single-digit chance of success.