I know many people have requested and asked for support for custom/more jars with Minehut staff denying it over and over but there's many reasons why we should have some way of using them
Allowing custom server jars gives servers more freedom and creativity beyond what regular jars allow, which in turn allows for more creative servers.
Minehut doesn't even need to directly add new jars to the panel or directly add full support for custom ones, just let us override the forced jar via SFTP or something, while allowing only paid plans or add a "hacky" way to do it. So that way, the average Minehut server user who has no idea what they're doing cant accidently break their server and only technical users would be able to do it at their own risk.
When external servers were very accessible, we could easily run private/custom server jars on our external hardware, now partners apps are gone and we're forced to overpay for Minehut's servers, its not possible anymore.
"Custom jars would be impossible for Minehut to update or manage"
Minehut doesn't need to do this, let this solely rely on the server owner themselves to update and manage their jar manually and ensure that it's working properly, we already do this outside of Minehut for every new version/patch.
"Custom jars would break and have compatibly issues"
Plugins already do this everyday and 100x more frequently, they crash, lag, break other plugins, have compatibility issues, break servers and countless other things
Custom jars crashing or breaking would have no effect on Minehut, only that server and the server owner, it's their responsibility to make sure everything is working, just like it's their responsibility to install working plugins.
"Custom jars are dangerous"
Minehut allows custom plugins to be uploaded unrestrictedly, there is pretty much no meaningful "danger" that is exclusive to custom server jars, especially when plugins can just modify the standard jars at runtime.