Does blockchain.info wallet or mycelium wallet use Bitcoin core? And if so what version? I am asking because on a website it was talking about invalid blocks and how you should have a newer version of bitcoin core for some reason.
https://bitcoin.org/en/alert/2015-07-04-spv-mining
When you use Mycelium you're not running a node on your phone. Instead they run a few Mycelium servers, which include Bitcoin core nodes. They will have updated by now (probably around the date of this alert).

Blockchain.info is notorious for running old or non-standard node software causing all kinds of corruptions in their block explorer, but also sometimes in their wallets. But even for them I'd be surprised if they haven't updated by now.

In general this alert is only still applicable if you're running your own node with one of the old versions mentioned.