Hi Yabuki-san,
Please check if new im-config 0.53-1 solves your issue. We included patch proposed at: https://salsa.debian.org/input-method-team/im-config/-/merge_requests/16 TBH, I am not even sure this is the right solution to your problem or any others. I have no idea how X session startup code are used by different DMs and I don't have enough resource (or time) to investigate this in depth. (GDM3 vs. LightDM) At least, this looks like a harmless patch which might solve double start of ibus. Regards, Osamu