almost all blocks are mined by this address, miner unknown: 12dRugNcdxK39288NjcDV4GX7rMsKCGn6B.
From block 721071 to 721087 there is only her, apart from a block 721083 hit by f2 pool.
I don't know where you got your data from but:
* I've checked 3-4 of those blocks and I didn't find that address you are talking about (for the coinbase tx)
* I've looked at coin.dance and it tells that most blocks were mined then by foundry USA, but not as many as you've stated; btc.com, antpool and poolin took a big share too