I'm struggling to find a free alternative, the others (Franz, Rambox) seem to be crippled until paid for. I wouldn't even mind paying, but their entry level tiers are around $6 a month.... Seems high for what you get
From what I've seen a/the maintainer was upset for not getting enough respect/thanks from the community and started causing drama. There've been issues for a while now; hopefully that's now over and people can move on to alternatives or start a fork where maintainers behave like adults.