This is the 12577th most frequent German word.
weichs
The word "weichs" does not exist in standard German. It may be a typo or dialectal. Did you mean "weich" (soft)?
'Weichs' is illustrating the softness of the ground after being soaked by rain.
Nach dem Regen ist der Boden ganz weichs geworden.
After the rain, the ground has become completely soft.
The adjective 'weichs' is used here colloquially to describe softness, specifically of toilet paper.
Ich kaufe immer weichs Toilettenpapier.
I always buy soft toilet paper.
'Weichs' is describing the texture of the cake, emphasizing how soft and moist it feels.