Washing machine smells like sewage

The exposed siphon has already been replaced. The question is actually why the draining process isn’t the same at all washing temperatures?

Because each program requires a different amount of water and therefore a different amount of water is drained. It’s just a theory, but for me the most plausible one since the washing machine is new and the drain is fine. It probably occurs more with intensive programs (cotton, higher temperature, etc.).

Sorry, but my washing machine has never washed at 90 degrees in over 11 years, and nothing smells.

When did the bad smell first occur? After a vacation or a longer break and a machine that was closed during that time (door and detergent flap), a foul odor develops. If that is the case, it is enough to dismantle the machine once, clean it thoroughly mechanically, and then everything will be fine again. The things are quite simple. It takes 2-3 hours to complete.

Since a new machine was procured after the odor issue arose and this still occurs afterwards, and since the smell does not specifically come from the machine but is present throughout the entire laundry room, yet is time-correlated with the machine cycle but only with certain programs, the conclusion by is likely that it has to do with the amount of pumped-out water. Starting at a certain amount, a suction is created in the wastewater system (inside the house) that presumably sucks dry a trap in the laundry room. To remedy this, as far as I know, a ventilation valve near the washing machine connection or an increase in the diameter of the wastewater pipe from the washing machine to the main sewer pipe can help. Also, check whether the branches on the downpipes are installed at a 45° angle (this is no longer done today, but 87.5°, precisely because of the suction effect). I am not an expert, just an experienced layperson.

Since a new machine was obtained after the odor case occurred and this continues to occur afterward, and since the smell does not come specifically from the machine but is present throughout the laundry room, but coincides with the machine's operation and only with certain programs, the conclusion by is plausible that it has to do with the amount of pumped-out water. From a certain amount onward, a suction is created in the wastewater system (inside the house) that presumably sucks dry a trap in the laundry room.
In my opinion, a ventilation valve near the washing machine connection or an increase in the diameter of the wastewater pipe from the washing machine to the main sewer pipe can help. Also check whether the branches on the downpipes are installed at a 45° angle (this is no longer done today, but at 87.5° precisely because of the suction effect).
I am not a professional, just an experienced layman.

You are right, it depends on the laundry and thus the amount of water. I tried washing only a winter jacket as a test, and there was no smell, but then with a full machine it reoccurred.