I created rails app in heroku environment and reindexed it to awsES via searchkick, but time out.

I created a rails app in heroku environment, but when I reindexed it via searchkick, it became timed out, so please let me ask you that question.

What's happening

When erokurun rails searchkick:reindex:all is multiplied via searchkick in heroku environment, the following error occurs:
I couldn't find any information about this error.

Error: timed out
    at TLSSocket.<anonymous> (/usr/local/Cellar/heroku/7.47.12/lib/client/7.54.1/node_modules/@heroku-cli/plugin-run/lib/dyno.js: 139:29)

environment:

heroku(hobby)
rails 6.0
Use searchkick
aws elasticsearch(t3.small.elasticsearch)

By the way, the number of documents I want to index is about 16000.

Is this probably due to the lack of memory in heroku's dyno?
Thank you for your cooperation.