I'm not sure if this is a bug report or a feature request. I'm currently running version 10.0.2 for Minecraft 1.21

I thought we used to be able to put filled buckets in the tank input and empty buckets would stack in the output. This doesn't happen in the latest version.

Likewise, I thought we used to be able to put a stack of empty buckets in the tank input slot and pull filled buckets out one at a time. This also doesn't happen in the latest version.

The ability to use bucket stacks was (or would be) a significant QoL feature. Manually placing and removing individual buckets for each fill or drain action is tedious and time consuming.

I'm trying to keep my playthrough as vanilla as possible. I'm only using the standard backpack for the convenience of portable storage, portable crafting, and tool swap. I do not intend to craft or use the hose, nor do I have any fluid storage mods loaded other than the tanks provided by Traveler's Backpack.

Thanks

Yes that's something I have in plans to implement, but I had some problems with it in the past. I'll try to implement feature once again

https://www.curseforge.com/minecraft/mc-mods/travelers-backpack-fabric/files/all?page=1&pageSize=20
Added in latest update