that is likely related to https://github.com/LemmyNet/lemmy/pull/5107, which limits the resolution of thumbnails.
the client you are using is probably only displaying the thumbnails to you, not the original images.
edit: this seems to include lemmy-ui as well
edit 2: raised a bug report for lemmy-ui
I'm not familiar with n8n but it's fairly straightforward on the API side.
You'll need a session token, also known as JWT, which you can get from logging in.
You typically don't want to do a login for every post, so you'll want to store that as a persistent value.
For authentication, you can pass the header authorization: Bearer {jwt}, with {jwt} being the session token.
https://join-lemmy.org/api/classes/LemmyHttp.html contains the API documentation.
You'll need to figure out the id of the community that you want to post to.
If you need to look it up, you can use getCommunity to fetch its details. Afterwards you can use createPost to submit it.
The form links for the methods explain the request body json values that should be provided.
photos will never be pngs unless someone intentionally converts them to that format, as pngs are much worse than jpgs for storing this type of image. pngs are much better for computer generated images, such as screenshots, drawings, etc. you can also losslessly compress pngs with tools like pngcrush without converting them to jpg.
it's like @[email protected] described. old content does not get federated unless there is new activity on it and someone on your instance is subscribed to the community it happens in.
this isn't anyone's fault, it's just a matter of the instance not being around that long that some historic content will be missing.
delegating authentication to another service.
one of the more commonly known options would be sign in with google, but this is also quite useful for providers hosting multiple services. a provider could host a service that handles authentication and then you only have to login once and will automatically get logged in for their lemmy, xmpp, wiki and other services they might be providing.
also adding my vote for the second one
this isn't true. it was incorrectly stated in the upgrade guide but has been removed a while ago. it was supposed to be a recommendation due to some issues with postgres 15. there is no postgres upgrade required between 0.19 releases.
Retaining old content has value
this 100%. this is exactly why i wouldn't recommend any communities to be removed if there is still content in there, worst case just lock it.
cleaning up communities doesn't make lemmy more active either. it may help to make active communities stand out more against inactive ones though.
cleaning up dead communities isn't a great experience as it is today.
admins could purge communities, but this can cause unexpected breakages with other activitypub software that is more strict about cryptographic verification, as purging a community erases all information about it from the local instance, including the cryptographic private key. purging a community also only removes it on the local instance, so other instances would still have a cached (although possibly marked as deleted) copy of it. this would be the only method that frees up the name to allow creating a new community under the same name later on. locally this would also remove all posts and comments associated in that community, but other instances may think that they have users subscribed to the community and may still have posts and comments in there. this also means if a new community is created with the same name again, the local instance will still not know about older posts, but users on other instances might see them still, and the local moderator might be unable to interact with them at all, e.g. to potentially remove old problematic content.
the next option is removing a community as (instance-)moderator action. this will only mark the community as removed without further impact. regular users won't be able to access the community on the local or any other instance anymore, but its contents are preserved in case it gets restored at a later point in time. the name is not released and there isn't even an error message shown when trying to create a new community with the same name.
another option could be to "take over" the community and delete it, which is the act of the top community mod deleting the community (not a moderation action). in this case only the same top community moderator can restore it. this behaves mostly the same as removing it.
none of these options are good to use. imo purging should be avoided in any case, and the other options both require admin intervention to release a community later on and have no user feedback in lemmy-ui at this time, at least on 0.19.5.
for communities entirely without posts it is probably ok to just remove them and restore and transfer them if someone requests them. for communities with content the next best thing might be locking the community, potentially locking all posts if it's just a small number, to prevent unmoderated new content in that community, and put up a pinned post asking people to reach out if they want to take over the community. otherwise, if the community was removed or deleted, all the posts and comments within them would also be taken down with the community.
It's not even just that. It seems that the extra @ acts as a separator, so you can't even autocomplete e.g. @threelonmusketeers@sh as that'll try to autocomplete @sh instead of taking the instance domain as part of the mention.
I've raised a GitHub issue for this now: https://github.com/LemmyNet/lemmy-ui/issues/2652
that is likely related to https://github.com/LemmyNet/lemmy/pull/5107, which limits the resolution of thumbnails.
the client you are using is probably only displaying the thumbnails to you, not the original images.
edit: this seems to include lemmy-ui as well
edit 2: raised a bug report for lemmy-ui