In below link, there are "There are other failures that can impact the indexing process itself and prevent the population from completing:"
phrase.
In that phrase, it explains that 'The full-text index exceeds the limit for the number of rows that can be contained in a full-text catalog.'
In this case, do you know how many number of rows is limited for full-text catalog? I didnt find any information about this limitation.
https://docs.microsoft.com/en-us/sql/relational-databases/search/troubleshoot-full-text-indexing?view=sql-server-2017