Such queries, if used within the ARN's JQL section, could be disastrous. It might mean that the add-on will try to retrieve 1000s of Jira issues & their required attributes. This can potentially slow down the host Jira instance & might as well bring it down if the search result set is huge.
Setting
To avoid this problem, by default, ARN applies a ceiling of 250 issues on every JQL. That is, every JQL section will only fetch a maximum of 250 Jira issues. But this can be a problem in genuine cases where a higher number of Jira issues are required in the release notes creation process.
As Jira admin, navigate to the Jira Apps menu >> Automated Release Notes under Configurations section >> App settings tab. Modify the Max Results(per JQL) setting, if required.