Archdevs, You move of both linux and linux-lts to the same kernel is bewildering. That eliminates all fallback capability lts provides. Currently, virtualbox Arch guests are broken on 5.10 (as with most other distros).
See: https://www.virtualbox.org/ticket/20055 With linux on 5.10 and lts on 5.4 it was workable to have lts guests. Now you have linux and linux-lts as the same kernel. How does that make sense? -- David C. Rankin, J.D.,P.E.