Linux framebuffer sometime show part of blue background

Description

I use lvgl7.0 with linux framebuffer.But sometimes the screen display part of blue backgrond in place not refresh realtime.

What MCU/Processor/Board and compiler are you using?

TI omapl138

What LVGL version are you using?

latest 7.11

What do you want to achieve?

do not show blue backgroud color

What have you tried so far?

dont even know how to start

Code to reproduce

I dont konw,but when exit app,it sometime show full blue backgrond.

/*You code here*/

Screenshot and/or video

If possible, add screenshots and/or videos about the current state

Discussed here: https://github.com/lvgl/lvgl/issues/2193