PPTX attachment 165754 [details] doesn't open good in LO 7.1+, seen in screenshot comparison MSO-LO attachment 165755 [details].
Looks like the problem of transparency.
Never was fine from OO to 7.1+.
https://git.libreoffice.org/core/commit/69842afcab0c5043c3c554493dd92d58c2bb02af from bug 136836, seen with git checkout db319c495cf1166af537d7054b0ddc23e17e46d3 in 7.1+ bibisect repo.
Looks like image is better now, but it shouldn't be white.
Build ID: a9976a958b2857e308c6598532151878615bfd9f
CPU threads: 4; OS: Linux 5.7; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US