The Bitcoin daily transaction count dropped by 42% in the last 10 days. The timing coincides with the end of Veriblock's testnet on March 4. While still in testnet, Veriblock captured anywhere from 25-45 percent of Bitcoin's transactions, according to Veriblock's self-published statistics.
VeriBlock is a startup that leverages OP_RETURN to secure alternative blockchain networks. Bitcoin enables anyone to embed 80 bytes of arbitrary data into its blockchain through OP_RETURN transactions. According to the whitepaper, VeriBlock’s Proof-of-Proof (PoP) consensus protocol “aims to enable a security inheriting blockchain to inherit the complete proof-of-work security of a security providing blockchain.” Bitcoin is the security providing blockchain that VeriBlock is starting with.
Some publications have suggested that the drop in transactions could be due to Venezuela's massive power outage. While it could be a small reason why the transaction count has declined, it is very unlikely that it played a significant role given how closely the decrease corresponds with Veriblock's statistics prior to the end of its testnet. Veriblock's mainnet launches on March 15 so the effect should be apparent then.