The rules are constantly changing - and so is the interpretation of these rules at the different stations.

Flying through the UK is a super bad idea right now - because of the extra hassles you’ll face on arrival in India - more paperwork, extra Covid test on arrival and depending on HYD’s rules interpretation of the rules a 6+ hour wait till you get your results there.

Then again you have to weigh it against a potential overnight in DEL or BOM if you fly UA or AI.