~ということになると (when it comes to)

The topic-setting idiom ~ということになると (also ~ということになれば), meaning 'when it comes to X / speaking of X / when we're talking about X'. Built on ~ということになる ('it comes down to the matter of X') plus a conditional ending — と (more conversational) or ば (slightly more formal/literary). Both variants are interchangeable. Used to introduce a specific domain before making a claim about it, often signaling that the speaker is about to comment on their knowledge or opinion regarding it.