Burnley got attendances of 19,784 and 21,762 in August 2019.
The average first day Championship attendances were down by about 2,000 on August 2019. I noticed Derby had a particularly small crowd compared to usual although there are of course other reasons for that.
So far this season, attendances seem to be massively down on pre COVID levels which is understandable. Burnley only had 16,000 there on Saturday so 5,000 below capacity and there has been a big reduction on usual attendances in the football league.