I'm not sure if this is related to the "bug fix" on Rake or some change to how camp HP/damage resist is calculated but your aren't the only person experiencing this issue. Mina is actually needed additional investment beyond Extra Spirit and T1 Rake to one shot the weakest Tier of camps too after 2-3 respawns.
The quick advice I can offer is, before or after procing Love Bites, use Cold Front to chip more HP off camps, it should help kill Tier 2 camps with more efficiency.
