From Adding Exceptions of Improving instance stability with rate limiting:

Allowlist the consumer key.

• Go to Administration > System > General configuration.
• Click Advanced settings.
• Enter the consumer key as the value of com.atlassian.ratelimiting.whitelisted-oauth-consumers. You can enter multiple consumer keys as a comma-separated list.

com.atlassian.ratelimiting.whitelisted-oauth-consumer seems to only support OAuth 1.0a application links

Workaround
Create an OAuth 1.0a link to the external application by selecting Atlassian product instead of External application during the application link creation screen. Selecting Continue after the warning screen will provide the remaining options for creating an OAuth 1.0a link