I've replicated this about 3 times on new Proxmox containers with a Debian Bullseye template.

On a brand new set-up, I followed the docker instructions and each time I run into the same installation error:

root@lemmy:~/lemmy# sudo docker-compose up -d
Creating network "lemmy_lemmyinternal" with driver "bridge"
Creating network "lemmy_lemmyexternalproxy" with the default driver
Pulling pictrs (asonix/pictrs:0.3.1)...
0.3.1: Pulling from asonix/pictrs
40e059520d19: Pull complete
123d533130d3: Pull complete
9b3248eff8f0: Pull complete
745f2087ad9e: Pull complete
6088f5378edf: Pull complete
Digest: sha256:1c2b9bdbce3e53b0a92eff90a04ade373e7d7e39dc71589d5729f786097898ed
Status: Downloaded newer image for asonix/pictrs:0.3.1
Pulling postgres (postgres:15-alpine)...
15-alpine: Pulling from library/postgres
8a49fdb3b6a5: Pull complete
397880efeff2: Pull complete
7981ad2d616c: Pull complete
4fd21bb223d9: Pull complete
5a558988fd88: Pull complete
64db87d2914a: Pull complete
ca2597ccb9a7: Pull complete
3d034ace2c79: Pull complete
Digest: sha256:bb2769783686897b370c061b4ad1aac5a819bccec7945d03c3b45a9b077bcea0
Status: Downloaded newer image for postgres:15-alpine
Pulling lemmy (dessalines/lemmy:0.17.3)...
0.17.3: Pulling from dessalines/lemmy
8a49fdb3b6a5: Already exists
0f2b6f690abb: Pull complete
85e2fd1d721c: Pull complete
Digest: sha256:cfa0b2d3f3b43784d3e69a9b06ff6ee4514625faf11c10936c7af1de9da104ce
Status: Downloaded newer image for dessalines/lemmy:0.17.3
Pulling lemmy-ui (dessalines/lemmy-ui:0.17.3)...
0.17.3: Pulling from dessalines/lemmy-ui
f56be85fc22e: Pull complete
761cd71a92ba: Pull complete
e460fd2efeda: Pull complete
ff35990e24b7: Pull complete
97f0ae9584a8: Pull complete
fbb07a8ed743: Pull complete
4f4fb700ef54: Pull complete
Digest: sha256:be6de0079f73a6495f077a560fafd19080aabcd77418397ce1534a18aee19f29
Status: Downloaded newer image for dessalines/lemmy-ui:0.17.3
Pulling proxy (nginx:1-alpine)...
1-alpine: Pulling from library/nginx
f56be85fc22e: Already exists
97c80f11709c: Pull complete
afb503c1f124: Pull complete
f8c948b732dd: Pull complete
d021bba29710: Pull complete
cadcca1af197: Pull complete
4aacde79cec4: Pull complete
Digest: sha256:2e776a66a3556f001aba13431b26e448fe8acba277bf93d2ab1a785571a46d90
Status: Downloaded newer image for nginx:1-alpine
Creating lemmy_postgres_1 ... error
Creating lemmy_pictrs_1   ... 

ERROR: for lemmy_postgres_1  Cannot start service postgres: OCI runtime create failed: container_linux.go:367: starting container process caused: process_linux.go:495: co
Creating lemmy_pictrs_1   ... error

ERROR: for lemmy_pictrs_1  Cannot start service pictrs: OCI runtime create failed: container_linux.go:367: starting container process caused: process_linux.go:495: container init caused: process_linux.go:458: setting cgroup config for procHooks process caused: can't load program: operation not permitted: unknown

ERROR: for postgres  Cannot start service postgres: OCI runtime create failed: container_linux.go:367: starting container process caused: process_linux.go:495: container init caused: process_linux.go:458: setting cgroup config for procHooks process caused: can't load program: operation not permitted: unknown

ERROR: for pictrs  Cannot start service pictrs: OCI runtime create failed: container_linux.go:367: starting container process caused: process_linux.go:495: container init caused: process_linux.go:458: setting cgroup config for procHooks process caused: can't load program: operation not permitted: unknown
ERROR: Encountered errors while bringing up the project.

After the error, the installation is aborted and no containers running.

root@lemmy:~/lemmy# sudo docker-compose logs > lemmy_log.out
root@lemmy:~/lemmy# docker ps
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES
root@lemmy:~/lemmy# 

I've tried as root, non-root, default config files, and updated with custom settings. No luck with any of those.

Any ideas?