I am experiencing an issue with Obsidian’s internal link autocomplete feature suggesting paths to non-existent files.
When I type a folder name to search for files within a specific folder, the autocomplete suggests paths to files that were previously in that folder but have since been moved or deleted.
Maybe you should try to remove the old link to the non-existent files? Maybe use some plugin like the Janitor plugin, or maybe Dangling links plugin. There are even other similar plugins, related to locating/working with links that are pointing nowhere.
The autocomplete wouldn’t suggest those files if there was some mention of them somewhere, so I reckon you need to deal with that first.
Also notice, that in general it’s kind of bad to try to use relative links in the vaults, as the vault by default doesn’t do relative links or shouldn’t need to care where the files resides. So maybe there is something related to that which is causing you grief…