My browser says (in F12 console of firefox):
SyntaxError client.js:2:1170023
hw https://лемми.опенсорс.рус/static/0799f19b/js/client.js:2
the file starts with
/*! For license information please see client.js.LICENSE.txt */
(()=>{var e,t,n,r,o={45850:(e,t,n)=>{"use strict";n.d(t,
and DeepSeek says that e,t,n,r,o should be separated by spaces, i.e. e, t, n, r, o
The lemmy.ml instance adds that image without problems.

I don’t know is it related or not. I have only one container instead of two, and I use Firefox instead of Chromium. Theoretically it’s possible that there is no enough access rights for images data volume, but I didn’t checked that yet (and in this case the error message is not clear and helpfull).
Yes, indeed! Please do check out the volume (bind-)mount permissions of the container.
Weird, that someone downvoted our messages. Perhaps, the person has life issues, unfortunately…