Bitcoin exchanges have their bitcoins spread out over 7 million UTXOs. Depending on the mining fee levels, this might cost some or many millions to consolidate.

https://i.nostr.build/WGRJk.png

Just now - since about 5h - OKX is consolidating some of their 1.3 million UTXOs, paying in excess of 500sat/vB!

https://i.nostr.build/Q7RJP.png