Sorry for the delay @Lin-Buo-Ren. This appears to be a regression that sneaked in when the chromium snap was rebased on core18. I can reproduce the problem, and switching to the stable/core16 channel fixes it. I’m on it.
This appears to be a bug in core18, for which a fix was merged already. I’ll monitor and test the next version of core18 to confirm that this is enough to fix the ibus regression.