Bitcoin Cash underwent its first block-reward halving yesterday. Profit-oriented miners were very quick to bail, as expected.
Coin Metrics shows the BCH mining rate falling off precipitously after the halving took place. 
The issue is that now the bch chain is more vulnerable to attack. To 51% attack bch it costs only $10,000! https://www.crypto51.app/
A similar scenario played out on Litecoin after it had its halving in August 2019.
With the upcoming big daddy bitcoin halving next month, can we expect to see a big drop in network security like we saw with bch and litecoin?
Progressively declining block rewards in pow coins sound good on paper and to investors who want a more scarce asset, but its clear the abrupt changes could damage the security of these chains over the long-term.