I had a setup where I pumped fuels from a tank into teleport pipe to a quarry far away. So far it was in another dimension. (if you're wondering, it was on the Moon) I spent almost 1 real life day waiting for the quarry to dig all the way down, and when I returned, I saw that tank fluid level was the same.

(There was no other fuel source coming from somewhere else, just two tanks connected to a single teleport pipe, one has finite fuel while the other is constantly filled by a refinery. The finite one never emptied. Can show screenshot of the setup if you want, but the reason is not the tank filling while it was being emptied. Fuel was gaseous fuel, the fastest consumed fuel. That tank should've emptied in only 45 minutes.)

Same also happened to a lava tank in the Nether, so it is not Galacticraft.

Same also happened in a quarry ~400 blocks away from the input pipe, so it's not because of being in another dimension.

I had a teleport tether placed in all of those input tanks.