Ethereum haven't really moved in a long time compared to the BTC increase. What can be the reasons for this? Are people not as enthusiastic about Ethereum as they were, or is because of new scalable projects on the Bitcoin blockchain?
Markets move in cycles. You could have said the opposite thing back in March of this year. In March, Bitcoin was reeling from a test of the previous all-time highs, combined with bad news about the ETF rejection. During BTC's ~30% correction at that time, the price of ETH rose 400%.
My general feeling is that news catalyzes price movement, but it doesn't dictate it. There was natural supply/resistance in the $1200s for BTC, and bears capitalized on the bad news to dump the market.
There is not currently much news to catalyze a price movement in ETH. However, the market has been consolidating bullishly for many months now. Sideways, with higher lows, coming off a major rally. I suspect that when the spotlight leaves BTC that some of that hype will move back to ETH.