MarsSeed [1] filed a deletion request for python-pillow-simd [2]:

This is an old duplicate of python-pillow, at version 9.2.0, whereas
repo's pillow is on 10.0.1 atm.

The fork project's README.md clearly states about their versioning
scheme [a]:

"
Pillow-SIMD is »following« Pillow which means it is drop-in
replacements for Pillow of the same version. For example, Pillow-SIMD
3.2.0.post3 is a drop-in replacement for Pillow 3.2.0, and Pillow-SIMD
3.3.3.post0 — for Pillow 3.3.3.
"

So as this AUR package is on 9.2.0 rather than 9.2.0.post[number], it
is using a copy of upstream Pillow's 9.2.0 source.

As one digs a little deeper, it becomes obvious that the fork project
no longer produces their patched versions of upstream's latest
releases. [b]

In fact, the last pillow-simd release was:
v9.0.0.post1 (Jan 4, 2022)
(seen on the second page of the git tags list [c]).
(Also on PyPI [d].)

The fact that the fork project has newer (vanilla, upstream) tags and
commits on GitHub than its Jan 2022 patched release is misleading. It
just means they mechanically pulled in ("copied") commits and tags
from the upstream pillow codebase, without maintaining their own fork.

As of now the fork repo's imported codebase is also out-of-sync with
upstream pillow: last pillow-simd imported tag is 9.5.0 (Apr 1, 2023),
as opposed to python-pillow's 10.0.1 (Sep 15, 2023).

In light of all the above facts, I posit that it is no longer useful
to keep this fork package.

Summary of the reasons:
- old duplicate of python-pillow,
- if reverted to pillow-simd 9.0.0.post1 (Jan 4, 2022), it would be
even older,
- not feature and API equivalent to pillow 10+,
- so it potentially breaks packages that rely on pillow 10's changed
or new API elements,
- all in all this can no longer be a drop-in replacement of python-
pilllow,
- fork is essentially unmaintained since Jan 2022.

[a]:
https://github.com/uploadcare/pillow-simd#readme
[b]:
https://github.com/uploadcare/pillow-simd/tags
[c]:
https://github.com/uploadcare/pillow-simd/tags?after=9.1.0
[d]:
https://pypi.org/project/pillow-simd/

[1] https://aur.archlinux.org/account/MarsSeed/
[2] https://aur.archlinux.org/pkgbase/python-pillow-simd/