The root cause of both is likely the same:
- Powerplay has brought a lot of people back to the game
- Powerplay has caused those people to go to systems they might not otherwise go to
- people playing the game in a system makes its BGS more active, by design
For an Anarchy faction, more players = reduced influence, in general.
For a non-Anarchy controlling faction, more players = increased influence, in general.
(And for Powerplay specifically, it incentives a lot of varied actions but
not in general the mission boards, which are the main way that non-controlling factions get influence in non-Anarchy systems)
Back then this was - iirc - taken care of
Back then there was a very specific problem - scavenger-class on-foot enemies belonged to the local Anarchy faction, and so harmed its influence when they died in large numbers. That was fixed by reallocating them to the generic "Pirates" faction.
The wider problem for Anarchies is that the game since the original 1984 Elite has
very strongly incentivised players to carry out legal over illegal actions, and that's not solvable by a little bit of rebalancing of how the BGS deals with those eventual outputs: that needs a complete rethink of what "legal" and "illegal" mean, what actions are incentivised and how, and so on.
(But also: I think Frontier's aim for "Elite Dangerous strategy games" has moved to more comprehensible and transparent ones - the Thargoid conflict, Powerplay - rather than trying to support as a balanced
game the emergent BGS play that players put on top of the "systems aren't static" background effects layer. There hasn't been a BGS rebalance noted in Patch Notes since Odyssey Update 10, back at the start of 2022, so almost three years ago)