Good news — there’s a quick fix you can apply yourself, no code changes
needed.

Go to Settings → Permalinks in your WordPress admin and click “Save
Changes”. You don’t need to change anything on that page — just click the
button. This tells WordPress to rebuild its URL rules, which is what got out
of sync.

Then open one of the affected posts and check the affiliate links. They
should show the correct /go/quotex format again. You may need to re-save the
post for existing links to pick up the new format.

One thing to be aware of: this can come back after a future theme update,
since the rebuild doesn’t happen automatically. If it does, the same
Settings → Permalinks → Save Changes will fix it again. When you’re ready, I
can add a small change to the theme so it handles this on its own — but the
manual fix works fine in the meantime.