Empty Bitcoin blocks occur when miners find a block using an empty template. Many pools send empty templates to miners because they’re faster to distribute, helping miners start work slightly sooner.

10.6% of all Bitcoin blocks to date were empty, the majority of which were in the early days when there were very few transactions. 

Over time this rate has dropped significantly, and now ranges from 0.15% to 0.5% at the network level https://image.nostr.build/40d41a07db11de81f8c7f02c40768dc1d90d13822db915cff84b68424193f4c7.jpg