Wallet is using internal addresses in a non-sequential way

[aesedepece]

I recently found out that most of my wallets have enormous gaps in their internal keychains. For example, there's this one wallet whose only internal address in use are 168, 171 and 178.

The impact of this is:

• [Mild] slightly slower sync in Sheikah
• [Severe] missing balance when the same key is imported into myWitWallet

[aesedepece]

Found out that this is related to fee estimation. Apparently, the pointer to the next internal address index is being updated upon issuing an estimate — which shouldn't!