Must have been something like that. Don’t know if you saw my original post before I deleted it, but navigating to either www.domain.com or domain.com, Opera was trying to load:
https://www.domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain.com/domain...
before giving up with a “too many redirects” error.
leading me to erroneously assume that the redir bit of my Caddy config was at fault.