This happens only on Fabric's Storage API.

When an import bus is in redstone pulse mode, it may initiate a Fabric transaction to transfer stacks. The pulse can occur due to any external stimulus however, and it's impossible to know if that external stimulus is part of an outer transaction or not.

This happens in conjunction with #1912 when the storage bus scanning a chest causes a neighbor update, and the import bus has not correctly considered a pre-existing redstone signal at its location (#5811)

Fixed in a71f29c