galaxy note 10

Almost the same here - Samsung Galaxy Note 10 Lite.

Very good point about the accessibility perspective regarding font size and contrast. I will also look into if the font should be replaced with a more readable one.

Do you also think that the letters and sliders are too small on the phone?

iPhone 15 Pro here and for me (old, eyesight finally starting to give up) they are a bit small and the contrast low - difficult to distinguish between the F and P in the middle channel of today's puzzle.

Could maybe do with the vertical bars being about 50% bigger and the letters scaled a bit more than that. Plus a high contrast option (white channels with black letters with white letters in the middle bit? Something like that anyway.)