A bidet attachment may add a tee between the toilet fill connection and its supply hose. That creates several joints close together. Water can track across the tee before dripping, so the lowest drop may be far from the first leak.
Identify the first wet joint
If it is safe to look, note whether moisture starts at the tank connection, the supply hose, or the bidet branch. If water is escaping, isolate the toilet at its shutoff if you can operate it safely. Avoid twisting the tee to find the source.
Bring the fitting details to the repair
Share the bidet model and photos of the connection. A plumber can check washer fit, thread compatibility, and hose alignment. Ask them to check all the joints after restoring pressure.
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