Batch exchange withdrawal to lightning requires covenants

Participants in a transaction can double-spend the batch by using a commit tx that spends from the previous funding output. This possibility should be expected, and therefore 0-conf cannot be used on the splice transaction. However, other than that, the splice transaction functions like a regular splice, and participants must monitor for double-spends while waiting for confirmations. There is a suggestion to not use nVersion=3 and pay 0 fees for this transaction, as it is considered a "standard" transaction and should instead use a reasonable feerate and nVersion=2.