Hello, so last september my car was overhating only on highway speeds, temperature went to 100,110,120celsius after I slowed down temperature returned back to 90, no engine lights, no fault codes, no dashboard messages about overheating..
Mechanic told me to clean the radiator.. which I did and car slowly stopped overheating.. but I think it was due to outside temperature because it was overheating during hot days, I cleaned in the beginning of winter and it was too cold outside.. so car was running just fine till now.. temperature outside starting to rise again and car overheating was back...

So they told me it should be thermostat.. yesterday my thermostat was replaced for original mercedes part

So far I didnt notice overheating but I need to drive more to make sure. But what is weird my temperature climb normally to 90°celsius, But sometimes it goes to 85,80 and sometimes even little lower when driving.
First thing I did I browse a lot of forum posts.. some people say its normal because its electrically controlled thermostat and it react by how agressive you drive and sometimes it cool the engine too much.. and some people said its wrong or maybe wrong thermostat.. but too many people had this problem makes me feel it could be normal? also I read some kind of software update might help, but Im not sure what to do