Canada

It depends; if by "electoral reform" you strictly mean switching to PR/RB without addressing provincial seat allocations (which assume FPTP), 7:50 likely isn't required, per the 2014/2016 rulings and recommendations (although they certainly would have faced challenges).

However, PR, and especially MMP, would naturally create an imbalance, necessitating either seat adjustments or additions (which increases costs), which could likely trigger 7:50. Any meaningful Senate or Governor General reforms would definitely require it.

That said, this was likely a moot point. ERRE recommended PR, but the Liberals preferred RB, ostensibly because it was easier to implement (and, not coincidentally, would have favored them long-term). The Conservative Senate caucus opposed any reform, while the ISG in 2018/19 - which Trudeau had aggressively pushed to be less partisan - was dubious at best just as the Liberals were losing ground before the election. Public sentiment was another obstacle; two years later, people occupied Ottawa for months over American border policy and Timbits, and largely coordinated disinformation campaigns. Pushing electoral reform then could have been a death knell for the Liberals.

It was an incredibly messy, uncertain process, costly both politically and legislatively, and still subject to Senate roadblocks and revisions had it passed. There was no simple path, even just for the ballot format portion of that reform.