It seems that these increases are (still?) short-lived. The last night the minimum fee went back to 1 sat/vbyte again. Now it's a bit higher but still not nearly as high as yesterday (currently 5 sat/vbyte).

Interestingly, according to this dashboard and also this one, Ordinals and Runes which had a small mini-wave in the last weeks, now are again taking less space. There's thus another reason behind the data transaction increase.

Are we about to see a new spam wave, perhaps these "non standard tokens" which deliberately violate the standardness rules of Bitcoin? See this post for more info ...