Do you know if your service is running under HTTP/1 or HTTP/2? According to this documentation, Cloud Run by default downgrades HTTP/2 requests to HTTP/1 when those requests are sent to the container. If you want to explicitly set your service to use HTTP/2 end-to-end, with no such downgrading, you can configure it for HTTP/2.
Here the limiting factor is that, if your service is running HTTP/1, HTTP/1 limits the request limit to 32 MB and that limit cannot be changed. Something that can be implemented is to configure your service to HTTP/2, since for HTTP/2 there is no request limit. In case HTTP/1 it's what's causing the issue, the first link that was provided in this post can be used to implement HTTP/2 to your service.