Copy & paste from LibraOfficeworks fine (baring the above issues). Copy & paste from OpenOffice fails weirdly (guess I need to fix that).
I've shared with @Chris D how that support has been done and a bunch of other samples.
Many thanks for your contribution; it is highly appreciated!
Yeah, adding AVIF support isn't particularly difficult but I'm not sure it's worthwhile just yet given the limited support.
Those planning to switch to either WebP or AVIF as their primary format will have to wait until both formats are available in XenForo because the switch requires real-life testing and comparison.
According to Can I Use, Edge is the only popular desktop browser that has not yet implemented AVIF, but the support should be coming soon (see “AVIF support is now available in Microsoft Edge”).