Surely, it could be both: the algorithm changes people’s habits and people change their posting habits based on the activity they think the algorithm is rewarding?
Certainly. The habit changes are just my anecdote. The anecdotes of others such as the mentioned photographers. They are two different perspective (consumer and creator) so I'm sure there are different experiences.
The consumer notices changes of their friends, who is posting what.
The creator notices changes in their impressions, how many is viewing what.
The consumer notices changes of their friends, who is posting what.
The creator notices changes in their impressions, how many is viewing what.