the "linkalho mod" only makes the config setting i already told him to do.
it does not fix or correct the issues with the account format linkalho injects are wrong/outdated.
if you insist that you have not linked a fake account, then most probably a new account flag was introduced which your emummc have not inherited, as it's not connected to nintendo in the same manner, but since the OLSC config does eliminate the issue, it is because it was trying to upload your saves, which only NSO members should have happen, and it is enabled by default (for NSO members)
tl:dr normally when you upgrade firmware (offically) your account data is sent as telemetry and receive what should be changed on i.e. starting games, most probably the account flags set in your systemsave for account data became obsolete, and your console is trying to obtain (by talking to nintendo) the newest format, but since it can't, it defaults to the default behaviour, which default behaviour is enabled, to (attempt) uploading your saves.
basically the exact same problem that people with fake accounts have, invalid/obsolete account flags