Part of the problem is that the more reputable hydroxychloroquine studies were abandoned based on an even more blatently fradulent paper in the Lancet claiming

Part of the problem is that the more reputable hydroxychloroquine studies were abandoned based on an even more blatently fradulent paper in the Lancet claiming it actually increased the risk of patients dying - like, it wasn't even some subtle statistical issue, there was no way the authors could've had access to the data they claimed to use and the number of patients supposedly in the study from some countries was implausibly high. So there wasn't really any good-quality evidence for a long time. Also, there's reason to suspect that the reason the Lancet was so willing to publish that paper is partisan; their editor-in-chief's Twitter had a blatant political axe to grind the whole time.