geosam [1] filed a deletion request for qgis-otb-plugin [2]:
OTB provider will be available in processing core starting from qgis 3.8, not available more.
[1] https://aur.archlinux.org/account/geosam/ [2] https://aur.archlinux.org/pkgbase/qgis-otb-plugin/
Request #16510 has been accepted by polyzen [1].
aur-requests@lists.archlinux.org