The issues section is the correct place and should be considered to be the dedicated forum for feature requests and bug reporting. It's designed for that sole purpose and gives instructions to issuers on how to reduce load when making a request. The devs will prioritize issues as necessary.
A Lemmy post or any Reddit-like forum in general is not good for requests since the posts will be forgotten over time unless they get cataloged on the issue tracker.
Interesting. My experience is that GitHub issues are very easy to moderate. It's easy to add someone to triage issues if that's an issue, and any load problems usually come from passionate issuers and commentators not following the rules rather than people making well thought out requests.
If there is a real load issue then there needs to be an announcement telling people about it to link to, since what currently exists are guides telling people to use the appropriate places for feature requests and bugs. You also can't tell people to not report bugs for reasons which should be obvious.