The command flash in the customize dialog should be remove as the font effect has been removed since LO 7.
Confirming with Version: 7.2.0.0.alpha0+ / LibreOffice Community Build ID: 41ff704cc49b7097b717882616011962ecd7198f CPU threads: 8; OS: Linux 5.4; UI render: default; VCL: gtk3 Locale: hu-HU (hu_HU.UTF-8); UI: en-US Calc: threaded
Gabor Kelemen committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/95d8eb87eb20351a2e5795fc8c16653c0f58d6b4 tdf#141995 Remove uno:Flash command from Customize dialog It will be available in 7.2.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
The option is gone now. Verified in Version: 7.2.0.0.alpha1+ / LibreOffice Community Build ID: b238522ca121ca8f863fe4d3394ade088a65ad01 CPU threads: 4; OS: Linux 5.8; UI render: default; VCL: gtk3 Locale: ro-RO (ro_RO.UTF-8); UI: en-US Calc: threaded