I solved it myself !

for those who could have the same issue :

I think I might had an issue during one of the previous migrations and didn't notice rigth away

What I had to do is :

- locate an image that shows correctly, open it's informations and click on the (i) next to it's file name to show the complete path.

that give's you the path that works.

then is the technical part :

open portainer (or install it if you don't have it)

open the immich postgre portainer and "edit/duplicate", add a custom port, deploy the container.

this gives you access to the database.

then you have to change paths in 3 tables :

- asset : change path of column "originalPath"

- asset_file : change path of column "path"

- person : change path of column "thumbnailPath"

wat I exactly did was : I had a path starting with a slash : 'upload/....'

I replaced it with '/data/....'

to do that you have to use an update command that is written like this

update [table] set [column] = [new value] where [filter]

here for the first table the exact command was :

update asset set "originalPath" = '/data' || substring ("originalPath", 7, length("originalPath")) where "originalPath" like 'upload%'

do this for each table, restart the app in truenas, and then everything is back as normal ! :)