In 2021 Twitter was encouraging free academic use of the API [0].

This was in line with long standing behaviors in this space [1].

Musk bought Twitter in 2022. In 2023, they began substantially restricting API access versus how it had been for years.

It is not unfair at all to look at that timeline, look at Musk's acquisition as the biggest change that had happened to the company in that timeframe, and draw a relationship.

[0] https://newsonline.library.vanderbilt.edu/2021/03/use-twitte...

[1] https://arxiv.org/abs/2404.07340