You have specified for 1 request to transfer 1000 products - such a request in the API completes about 160-170 seconds.
And with a subsequent request (for the next thousand products), we get either the error {"status":"HTTP_ERROR","response":{"code":429,"message":"You hour requests limit has been exceeded. Retry after 2969 seconds "}} , or an error {"status":"ERROR","response":{"message":"Unknown server error. Please let us know"}}
All this can be seen in the log
https://crm.dobavki.ua/admin/logs/showall/ajax/?file=horoshop-2021-08-03.logActually, I can’t give you a solution to speed up and increase the limits of the third-party API