Odd that some type of debris went right into your water heater and instead of just sitting at the bottom, managed to slow up the hot supply to your tub.
I would shut any valves for both cold and hot to the tub, remove the hot stem in the tub (if applicable), slowly turn the water on to flush any debris out.
If the water comes out normally, you probably flushed the debris out, if not, then there could be something trapped at a valve, than you would need to pull out the valve stem and flush that out
It's also good practice once every other month or so to get a metal pail or bucket that can handle hot water, place it under the lowest drain valve at a water heater and open it till any dirt, debris, rust or whatever is done coming out, usually anywhere from a half gallon to two gallons, if the water heater hasn't been flushed in a long time.
You may also want to make sure the water supply to your furnace, dishwasher, washing machine and anything else supplied by the line you repaired is flowing properly.
Good luck
