I looked at the relevanssi settings, but it is not in English 🙁
How did you remove relevanssi? Did you use the WP deactivate and then delete and click the button to remove all the data? For some reason, I think it is not doing this. after deleting it, look in the database for these tables:
wp_relevanssi
wp_relevanssi_cache
wp_relevanssi_excerpt_cache
wp_relevanssi_log
wp_relevanssi_stopwords
If they are still there, you probably need to drop the wp_relevanssi_* tables.
You can remove all the options from wp_options:
delete from wp_options where option_name like 'relevanssi%' limit 100;
But note that table names will be different if you are using a table name prefix.