What to do ?

Check if the Scaling factor applied to the display is 100%.
The scaling factor can be found at: Settings -> Devices -> Displays -> Scale

Why ?

Scaling mechanisms which are based on the dpi-count have an effect only on individual control elements. So, if the Scaling factor is not 100%, this leads to scaling of the individual GUI elements (text, buttons, etc.) as in this case.

Optionally, a 2nd monitor with a different, more suitable resolution (which does not require any scaling) for CM can be used. This allows retaining a higher scaling factor on the main monitor, thereby ensuring that the other UI elements are of a suitable, readable size.