I have found the problem. One of the plugin files was seemingly edited, and those lines appeared on top of it, see this: https://i.imgur.com/Og6WA40.png
It looks like as if the group permissions or file permissions were changed on another file or an 'ls' command was run via SSH, and outputted to this file. Anyways, I have removed those lines, now it will work without problems. Please keep in mind that those lines were put there externally, as the plugin does not contain them, I just double checked.
This should not re-appear, but if so, then I recommend checking your bash scripts, in case you run any via SSH. But I think this was only accidental, and probably will not appear again.Best,
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