You can ask for a review of your I&E. If this shows the IVA to be unaffordable you can ask for it to be closed based on payments made to date ( basically calling it quits). If they do not agree to this course, creditors can ask that the IVA be failed, as your argument is that you can no longer make the payments. I cannot see them gaining anything from doing this --- but the risk is there.
I actually did this when I suddenly became a single parent half way through my IVA --- and creditors agreed. But, of course, every case is unique.
The Insolvency Service have issued new, temporary, guidelines relating to Protocol Compliant IVA's, where they have made an agreement that IP's can consider a reduction in monthly contributions of up to 50% of the current payment. or £75, whichever is higher. There are, of course, "Ifs, buts and maybes". The announcement and full details can be read here: https://content.govdelivery.com/attachm ... 202022.pdf
Our friends at Debt Camel have also written an article which explains the changes, here: https://debtcamel.co.uk/help-ivas-cost-of-living/
Which is a far easier read ---- maybe something there might help.
I am not qualified to give advice and can only state my opinions, based on my IVA experiences.