I've managed to reproduce this issue on an affected Firefox nightly from 2020-03-02 on Ubuntu 18.04x64. This issue is verified fixed on Firefox 76.0b4 using Windows 10x64, Ubuntu 18.04x64.
Bug 1619318 Comment 13 Edit History
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I've managed to reproduce this issue on an affected Firefox nightly from 2020-03-02 on Ubuntu 18.04x64. This issue is verified fixed on Firefox 76.0b4 using Windows 10x64, Ubuntu 18.04x64 and macOS 10.15.4.