The wallet RPC settxfee sets the fee rate for a wallet.

Current help text:

Set the transaction fee rate in BTC/kvB for this wallet. Overrides the global -paytxfee command line parameter.
Can be deactivated by passing 0 as the fee. In that case automatic fee selection will be used by default.

Arguments:
1. amount    (numeric or string, required) The transaction fee rate in BTC/kvB

Result:
true|false    (boolean) Returns true if successful

This is a misnomer, as stated here #29278 (comment) so should instead be setfeerate

@jonatack suggested a safer approach to avoid breaking things

(see: #20484 (comment)). I think this is better approach than just renaming the settxfee RPC to setfeerate?

• Add setfeerate RPC which is a mirror of settxfee but in sat/vB.
• Keep settxfee hidden, but prefer the setfeerate RPC in future use.
• Eventually deprecate settxfee.

This issue is limited to fixing the ambiguity in settxfee.