Bathroom planning assistance

The apartment building in which we purchased an apartment is currently under construction. The current plan is that there will be a laundry room in the basement, where each apartment has a space for its own washing machine/dryer. In addition, connections for a washing machine and dryer were planned in the storage room of our apartment, as we wanted the machines inside the apartment. Now the electrician, who apparently is also on the council of the local housing cooperative, has pointed out to us that we definitely should not place the washing machines in the small storage room. Mainly because of moisture and the risk of mold. The storage room has shell construction dimensions of about 1.5m x 1.55m, so 2.33 sqm. There is supposed to be a fan installed there, but he still sees it critically because there will also be "technology" in the room (the apartment’s network cabling comes together there, etc., and the fuse box is also in that room).

Now our question: How problematic is the moisture issue? And if the washing machines really should not be placed in the storage room, could they somehow be placed sensibly in the bathroom? There would not need to be a washer/dryer stack, but rather we would more likely use a washer-dryer combo that has both washing machine and dryer in one unit.
This is the current bathroom layout:



And this would be an idea from us with the washing machine in the bathroom... but here the question would also be whether this "works" or is rather not sensible?



It should be noted that the dimensions of the red walls around the shower remain the same as in the current plan (i.e. 1.52m instead of 1.42m and 45cm instead of 55cm), here they are just "old." Also, hopefully, the bathtub would be oriented the other way so that one looks into the room and not at the wall.
In addition, we would make the pre-wall only about 1.50m long at the sink and have no pre-wall for the washing machine, if that is somehow possible. The water connections for the washing machine would then come out sideways from the pre-wall so the washing machine could be pushed further back.

I have now had my washer-dryer in the storage room of my apartment for 5.5 years. It is about the size your room is supposed to be. There is also a fan installed there that extracts the moist air. I even installed a rod above the washing machine where damp blouses/T-shirts etc. can still dry hanging on hangers. Nothing molds there. In that room, there is the electrical fuse box and the underfloor heating distributor. In addition, there is my supply shelf on one wall, also for things like toilet paper, kitchen roll (which do not get damp). The vacuum cleaner and mop are also kept there. For the bathroom .. between the tub and the shower, I would put a towel radiator on the left wall. At my place, it is also only connected via the underfloor heating.

You even partially dry laundry in there and nothing gets damp?? Then the scaremongering about moisture surprises me.... Do you always keep the door open there or how do you manage it? For us, this storage closet is directly in/by the kitchen, which is in the open kitchen, dining, and living area. Regarding the bathroom, yes, a towel radiator is currently planned, but with an electrical connection.

Exhaust air needs supply air, i.e., when my Miele washer-dryer is running in the drying cycle, noticeably warm and humid air is generated, which is then removed by the exhaust fan. That is truly extracted air in my case. And of course, air must flow in to replace it. Usually, the gap under the door is enough; if I want it faster, I leave the door open and open a window somewhere. There are also variants where a ventilation grille is installed in the door.

The items I sometimes dry in that room are already pre-dried using the smoothing function of the dryer.

Otherwise, I should maybe mention that I live in an old building, but with new windows.

The same moisture would arise in the bathroom. And the house design seems to handle that well. So why not with the storage room?

Well, to be precise, the electrician said I shouldn’t install washing machines in the bathroom either because the new houses are so airtight.... His opinion: in the laundry cellar. I just thought maybe rather in the bathroom because there is at least a window and the room is also much bigger.

Bad is better. Windows, more volume. Otherwise, does the electrician also forbid showering? Because water really gets everywhere, especially with warm shower users. Karsten