My first layers started to have these "seams" in them. I am printing on the Anycubic Ultrabase.
Any other layer is fine.
Has anyone else experienced similar problems or an idea of how to debug this issue?
The picture is of PLA (BQ Easy Black) printed at 215 °C on the Ultrabase. The the same issue with BQ Easy PLA red, turquoise and white (205 °C), Zaper PETG Brown 230 °C and HobbyKing translucent ABS Red (245 °C).
Changing the nozzle did not change anything.