print quality - What causes ripples on part of first layer? - 3D

I'm having issues with ripples on the first layer of big flat prints. The initial corner of a big flat print is fine, but then ripples begin to form as shown in the screenshot. I'm just a newbie

Wavy lines / ripples in top layer - Page 2 – How do I print this? (Printing help) – Prusa3D Forum

Strange ripples at the end and start of each layer - Improve your 3D prints - UltiMaker Community of 3D Printing Experts

AnkerMake Explore the 3D Printing Frontier - Ankermake Canada

Confused. Looks like underextrusion and overextrusion in one print. : r/FixMyPrint

ripples on top layer now, too! – Others (Archive) – Prusa3D Forum

3D Printing First Layer Problems - Ankermake US

3D Printing First Layer Ripples: How to Smooth It - First Layer Problem

Odd first layer fill - 3D Printing / 3D Printers - Talk Manufacturing

Wavy lines / ripples in top layer - Page 2 – How do I print this? (Printing help) – Prusa3D Forum