opam-ci jobs getting stuck

There's something off currently with opam-ci.

This simple PR with a 1-line change to a not-so-popular package https://github.com/ocaml/opam-repository/pull/27489 I opened 4 days ago
yet I'm still waiting to the 2(!) reverse dependencies to get a machine resource and complete it, without having (force) pushed any additional changes:
https://opam.ci.ocaml.org/github/ocaml/opam-repository/commit/0c3833ec790dccac0c74b91d4c8004e673420389

• gluon.0.0.8 (active) https://opam.ci.ocaml.org/github/ocaml/opam-repository/commit/0c3833ec790dccac0c74b91d4c8004e673420389/variant/compilers,5.3,bytestring.0.0.8,revdeps,gluon.0.0.8
• gluon.0.0.9 (active) https://opam.ci.ocaml.org/github/ocaml/opam-repository/commit/0c3833ec790dccac0c74b91d4c8004e673420389/variant/compilers,5.3,bytestring.0.0.8,revdeps,gluon.0.0.9

I've had to wait before, e.g., when being unlucky and publishing on top of a dune or a JaneStreet release, but even then, the waiting time has been ~1 day or so.

The problem is not restricted to the above PR. I see a couple of other PRs seemingly stuck and waiting to complete:

• https://github.com/ocaml/opam-repository/pull/27484 - stuck for 5 days
• https://github.com/ocaml/opam-repository/pull/27455 - also seems stuck for ~5 days

Start with the opam-ci commit and variant links in the issue, then compare the stuck jobs for gluon.0.0.8 and gluon.0.0.9 with the other referenced pull requests. Determine why jobs remain waiting for machine resources and verify that affected reverse-dependency jobs can acquire resources and complete.