Cuse wrote:

Is it possible somehow when the water was drained it caused some
sediment to be stirred up and one big piece is somehow flushed into the
hot water outlet and stucked somewhere, causing the reduced pressure?

Sum


It sounds like you have a gate valve and the somehow you
managed to pull the stem loose or something with the valve
mostly closed.

You keep looking for other answers, but everything you say
points to only one thing.

Repeat after me: It's the damn valve. I will replace the
valve. It will fix the problem. I will replace the valve, I
will replace the valve.