Vancouver has a plant that harvests heat from sewage to provide district heating and hot water (https://vancouver.ca/home-property-development/how-the-utili...) - you don't need super high temperatures for it to be useful. During construction there was talk that the Telus building downtown's in house data centre providing heat to the attached condo building (https://www.datacenterknowledge.com/servers/telus-warms-cond...) - I'm unsure if that actually went ahead.

Fundamentally, a limit on doing it at scale is that it for efficiency it requires the heat to be consumed near the production - and the bulk of large power intense data centres are not located in the midst of high density residential neighbourhoods with a demand for heat.