Dear Maintainer,

Unfortunately Threads accounts have two (possibly more) aliases by
default, and they
can't seem to decide which one is the canonical one.

toot follow @24zzz_ig@threads.com

doesn't work [despite this being the username on threads' side]

toot unfollow @24zzz_ig@threads.net

does work

[this might be an alias thing??]

but generally: toot unfollow @24zzz_ig@threads.com
@24zzz_ig@www.threads.com @24zzz_ig@www.threads.net
@24zzz_ig@threads.net should all do the same thing.  And yes, threads
is a big enough instance that they should be handled as a special
(annoying) case [up to 99% of fediverse users are on threads]