Question about Ctek MXS 5.0 (CH version)

The device does not have a CAN-BUS and therefore cannot be used with the BMW board socket. It is suitable for direct connection to the battery

The manual and the BMW-only chargers are merely brand protection. Because BMW also uses a battery from a third-party manufacturer, they can be charged with any halfway normal charger. It is much more important what type of battery it is. Lead acid open or gel or AGM .... or whatever. And, lithium batteries would need a different charger. Warm up? My CTEK for a 120 AH battery got hot. For the motorbike with maybe 15 or 20 AH, it will certainly get a little warm if the battery is heavily discharged. So just go for it.

So I bought the Ctek 5.0 for my 2021 F GS. I haven't read anything like that about only "BMW Original" being recommended/used for charging, but I think it's the same as with the engine oil, which is also "exclusively" recommended for use by BMW.
Regarding the heat, I would have to look it up, I didn't pay attention to it, but it makes sense that the charger gets warm, as it can then give off the unused current that it generates in order not to break itself...

Energy guzzler?
1kWh costs 20Rp.
Every charger gets warm. Also pay attention to your mobile phone, because the adapter and the mobile phone get warm....