The update for the Apex Legends Chaos Theory event included a lot of changes, and according to multiple player reports it seems that more secret nerfs were included to both Bangalore and Caustic. On the surface, the two Legends almost have nothing in common, but they both bring concealment to the battlefield with their smoke.
After the update, some players had noticed that both Bangalore's smoke and Caustic's gas were a bit easier to see through. First thought to be a bug, it was later confirmed that this was an intended change to both Legends' arsenals.
Apex Legends Secret Nerfs Included in Chaos Theory Update: Bangalore and Caustic
Respawn Developer Eric Hewitt confirmed that the particle FX had been altered to redefine the visuals of both smokes. Additionally, this was confirmed to be the case for smoke effect left by Gibraltar's Ultimate.
The idea was to create less density within the smoke effects, making it easier to see solid objects within them. Both Caustic and Gibraltar had already received some changes in this season update, but Bangalore's update is unprompted.
While Bangalore's kit has been used more reliably earlier this season, this change will likely see her used less as Season 8 continues. Odd that an update would affect an already under utilized Legend with no reasoning behind it disclaimed so far, but nonetheless the update is here.
More updates to Legends have been confirmed for Season 9 already, so perhaps this update to Bangalore's kit will be reversed secretly once more.