I mean this is obviously a joke thread, but I'll play along.
- Way higher volume of fights than there used to be (particularly in UFC).
- Low leg kicks have become way more popularized in recent years. Fighters are just spamming low kicks into calves, and often shins/knees.
- Fighters becoming more skilled at checking said leg kicks = way more hard bone on bone leg contact
Otherwise... it's just anecdotal, there's no data necessarily indicating that there's more bone breaks. We also just hear about a lot more stuff these days than in the past with social media and fights on youtube, etc.