The application lets you configure a proxy, and then does not use the proxy. It ignores the proxy configuration without informing you. It silently ignores it. No amount of comments in a bug tracker changes that.
Oh but I don’t blame him either, it’s not a question of pointing fingers.
Saying it’s “likely isn’t used by the majority“ is bad form, in my opinion. You don’t know that. I don’t know either, to be sure, but it makes me personally lose faith in the security aspects of the project.
I support him on Patreon (https://www.patreon.com/deluge_cas) where he sometimes posts updates but it's clear that he's very busy with other things (Including going through an illness) so I'm not blaming some open source maintainer for picking up a 10 year old, apparently hard to reproduce issue with a total of 45 comments.
The client can be used just fine, except for a small buggy behaviour in case if you are using a proxy which likely isn't used by the majority of users.