Water trickling from hot taps even when WH cold line is shut off and disconnected.

I'm in the process of replacing my water heater.

I shut off the cold water supply and hooked up a garden hose to the drain valve, opened it, and then opened a few hot water taps around the house. I left it like that for a while and it eventually fully drained and the flow from the garden hose stopped.

I left it like this overnight and the next morning I noticed there was water trickling from the garden hose again. I checked my doorbell cam footage and sure enough at some point it just started slowly draining again. I then also noticed that all of the hot water taps around the house were trickling water out too.

I figured maybe the cold supply valve was leaking but after disconnecting the cold line, it was dry. I disconnect the hot line and it's backfeeding some water, like a slow trickle. I stick a bucket under it and let it drain for an hour and it didn't slow down at all.

I went to every faucet in the house and shut it off and the trickle out of the hot line was unchanged.

I even go to the street and shut off the water main and while the trickle slowed down, it kept going.

What do you think could be going on here? Do I have a combination of issues or is there one thing that could explain all of this?