Mixed content error

We have an on-prem instance of Sentry hosted on a non-secure protocol (HTTP). Our other web applications are on secure protocol (HTTPS).

We have the Javascript side of Sentry enabled on one of our projects and I am getting this error:

Mixed Content: The page at 'https://domain.com/app.php' was loaded over HTTPS, but requested an insecure resource 'http://sentry.domain.com:9000/api/2/envelope/?sentry_key=<sentry_key>&sentry_version=7'.
This request has been blocked; the content must be served over HTTPS.

We are unable to move our Sentry instance to HTTPS. I just don’t understand this error because I’m including our Javascript file using HTTPS because the JS bundle resides on the web app.

Is there a way to fix this without having to move our Sentry instance to HTTPS?