Let's try. First, some magenta cast is indeed "normal" when you use wide-gamut displays with non-colour-managed apps.

If your "need" is only sRGB (and Rec.709), then it would make sense to buy a "normal" (i.e. sRGB) monitor. This is particularly true if you edit video, because the output colour management for video is less common and more demanding. It does not guarantee that you get correct colours, but at least you'll get "normal" colours that most people get, without oversaturation, even if the app is not colour-aware or if you don't set up colour management. Still, it's better to get a decent monitor that explicitly declares sRGB compatibility (and not just "coverage"), like that Benq PD2500Q you mentioned.

That said, wide-gamut monitor is, by definition, more capable. But you will have to become "colour aware" yourself, and be very careful in selecting the apps you use and setting up the colour management (in the OS and in each app). Ideally, you should buy a colorimeter and profile your monitor. (This will certainly be cheaper than buying another monitor now).

Now, some technical details. If your monitor claims "deltaE < 1" everywhere (which I find a bit hard to believe), it must specify with respect to what. Presumably, the monitor must be in its "native" colour mode without any adjustments, and you must use an ICC profile they supply. This profile is not stored in the display; it should come as a file on a disc or download, and you must install it in your OS. Check the manual carefully. Then, and only if you use a colour-managed app, you should see correct colours without a cast or oversaturation. Note this does not normally apply to the desktop and GUI: they are usually not colour managed. If you are comparing with another monitor side by side, you should use a photo or a test chart open in a colour-managed app (on both sides).

Alternatively, if your monitor has a dedicated sRGB emulation mode (and you intend to trust it), you could use it. In this case, you need to tell the OS that you have such monitor by installing an sRGB profile in the OS; or, alternatively, you could remove any ICC profile and thereby cancel any colour management. (This latter is not that good because you'll see desaturated colours for images that are created with wider gamut, which is not that uncommon today).

If you don't like sRGB emulation now, it could be two things:

• You did install the full ICC profile and are applying it (i.e. viewing a photo in a colour-aware app). This would result in desaturated colours, because the OS believes the monitor is wide gamut whereas it is actually not (in the sRGB mode). Always remember that the ICC profile applies only to a specific mode; even if you change brightness, it may potentially shift colours. For this reasons good monitors lock most or all adjustments once they are calibrated.
• It is actually correct (more or less) but you don't like it. This psychological effect is rather common when you switch from bright saturated colours to limited colours. (Just like we perceive louder music "better"). But remember that colour management is about correct colours, not "nice" colours.

You can only be sure what is the case if you profile the monitor with a colorimeter and then don't change any of its settings. Note that monitors gradually change colours as they age, especially when new, so ideally you'd need to do it periodically.