If both hot and cold water pressure drop together, the issue might be a general supply problem or something in the main line. But if your cold water is fine and only the hot water side becomes weak, the problem is likely closer to the geyser or its immediate plumbing.
It could be a partially blocked inlet filter, mineral buildup inside the heater, a failing mixer, or an issue with a specific valve. Telling a plumber, “Cold is normal, hot is weak,” gives them a head start. They don’t need to check every line in the house; they can focus on the hot water system.
Observing this detail—and writing it down before you forget—saves diagnostic time, which often means faster, cheaper repairs.