It is here at the moment and the govt have issued this, which you might find helpful:
https://www.gov.uk/guidance/avian-influenza-bird-flu?utm_source=dca2a804-f7e9-43a4-8b4a-e67d9e2ca7ca&utm_medium=email&utm_campaign=govuk-notifications&utm_content=daily#how-to-spot-avian-influenza
hello @kekofarmbanten ; welcome to BYC :frow
Generally a purple comb indicates a blood circulation problem, but what has triggered that in your birds' case is what we need to find.
I will alert some of BYC's experts and hopefully they may have some ideas, @azygous @coach723 @dawg53...