Knots? AFAIK ir has the same estimator as Core, haven’t noticed big differences in estimations. Maybe @Luke Dashjr can comment. Don’t also Sparrow Wallet have custom estimator?
Also Wasabi coordinator takes mempool into account. https://github.com/zkSNACKs/WalletWasabi/pull/10734
Only difference between Core and Knots fee estimates is Knots by default targets confirmation within 24 hours. Looking at your current mempool for fee estimation is broken by design