To add some clarity. There have been a few factors that are causing this.
- The referral program was being abused and resulting in one-sided liquidity additions to the primary curve pool. This is being addressed with the whitelist proposal here: Switch Referral Program to Whitelist Mode
- There have been some recent projects that have been offering high APR on native ETH and the liquidity vampire swarm has removed ETH out of the curve pool as well (similar to one sided staking). These have already decayed drastically as the rewards have turned off and will take a week or two to distribute back to the ecosystem. Hopefully that finds its way back to the curve pool as well but not for sure.
Lido is working on increasing utility (Aave, Maker) and incentivizing tighter liquidity bands (Uni V3). This will take a little time but is a priority for the DAO to correct. As more utility is found with stETH the peg will continue to become stronger.