could this problem be caused by the absence or misconfiguration of an SSL certificate for Meilisearch?
I don’t think so - your Meilisearch instance at https://meilisearch.open.kaznu.kz appears to be working fine.
Is it possible that you just need to (re-)create the Meilisearch indexes? You could see 400 errors if the indexes do not exist. If so, you just need to run tutor [local|dev|k8s] exec cms ./manage.py cms reindex_studio --experimental . For more details, see "Library Components Created Successfully but Not Displayed After Sandbox Upgrade from Sumac to Teak — Possible Meilisearch 400 Errors?" - #2 by braden