I’m getting the same error in an esp32_ported version of LVGL, that I had with the v7.1 port.
See topic: https://forum.lvgl.io/t/lv-label-set-text-fmt-outputting-f-on-display-and-not-the-actual-text/4164
On the master branch of LVGL the KConfig is missing the the following entry:
If there is another setting now, please let me know.