Knots? AFAIK ir has the same estimator as Core, haven’t noticed big differences in estimations. Maybe nostr:npub1lh273a4wpkup00stw8dzqjvvrqrfdrv2v3v4t8pynuezlfe5vjnsnaa9nk can comment.
Don’t also Sparrow Wallet have custom estimator?
Discussion
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