I can think of lots of reasons:
Inaccuracies with the census (using 2011 census when there are probably a much higher proportion of BAME in this country in 2020)
44% of doctors in the UK BAME
25% of nurses BAME
(NHS are superspreaders so family impacted)
BAME more likely to work on the frontline, eg taxi drivers, bus drivers, care workers, and in jobs where you can't WFH
Minorities tend to be poorer, and that's associated with poorer health
BAME in the western world more likely to suffer from Western diseases like diabetes than their white counterparts
Unconscious racism leading to poorer care for BAME in the health service
People have mooted vitamin D deficiency
More likely to live in overcrowded housing
BAME more likely to live in big cities like London and not out in the sticks. London etc hotspots due to overcrowding and public transport a necessity.
I can go on and on....