Repeated mipmap non-power-of-2 warning from Canvas UI on stable

When I'm playing FG 2024.1.6 on Linux, it becomes slow and unresponsive when repeated warnings appear. This bug occurs on all aircraft. The repeated warnings from fgfs.log:

  321.95 [WARN]:io        /builds/flightgear/fgmeta/simgear/simgear/scene/material/mipmap.cxx:276: mipmapping: texture size not a power-of-two: /mnt/f/Env/flightgear/data/fgdata_2024_1/gui/styles/AmbianceClassic/widgets/backdrop-button.png
  322.01 [WARN]:io        /builds/flightgear/fgmeta/simgear/simgear/scene/material/mipmap.cxx:276: mipmapping: texture size not a power-of-two: /mnt/f/Env/flightgear/data/fgdata_2024_1/gui/styles/AmbianceClassic/widgets/backdrop-button.png
  322.02 [WARN]:io        /builds/flightgear/fgmeta/simgear/simgear/scene/material/mipmap.cxx:276: mipmapping: texture size not a power-of-two: /mnt/f/Env/flightgear/data/fgdata_2024_1/gui/styles/AmbianceClassic/widgets/backdrop-button.png
  322.03 [WARN]:io        /builds/flightgear/fgmeta/simgear/simgear/scene/material/mipmap.cxx:276: mipmapping: texture size not a power-of-two: /mnt/f/Env/flightgear/data/fgdata_2024_1/gui/styles/AmbianceClassic/widgets/backdrop-button.png