It’s turned out mariadb-dump is 10.19 in the mariadb’s 10.11 docker image:
snikolaev@dev2:~$ docker exec db-test mariadb-dump --version
mariadb-dump Ver 10.19 Distrib 10.11.10-MariaDB, for debian-linux-gnu (x86_64)
Then the question is if you can reproduce the issue using the dockers way I showed and let me know how I can reproduce it on my end? Or perhaps the issue is just solved in the dev version of Manticore - Manticore Search Manual