The displays T-CON logic capacitors have degraded so the scan is skewed. I would live with it as getting a new screen is expensive! Here’s a recycled unit [https://beetstech.com/product/thunderbolt-display-27-2011-lcd-display-panel-661-6028?gclid=Cj0KCQiA3Y-ABhCnARIsAKYDH7tgwz9HGIxELTkMdMz612Za7p_lBmV81a7jpHNkqByF6BKd0pDo81caAj0lEALw_wcB|Thunderbolt display assembly, Apple P/N 661-6028, LM270WQ1 (SD)(B3)]