I just solved what was becoming a very aggravating issue thanks to the help from the folks in the #weechat channel in Libera.Chat. On OpenBSD, my weechat client would put a question mark to separate the nicks and the messages sent with a question mark instead of a pipe-looking character like it should. It looks like this was caused by opening weechat without having the correct locale set. By default, OpenBSD uses a locale of C, which only supports ASCII characters.