KB5008631 broke eDiscovery in Exchange 2013 for me and several others. I opened a support case and support responded "don't worry, it's already been fixed and flagged for the next CU". I knew what that meant even though they didn't. Several months later, eDiscovery is still broken because the fix has not been released. Now support is telling me not to expect the fix because Exchange 2013 is out of mainstream support. Except eDiscovery was working when Exchange 2013 exited mainstream support. Breaking something with a SU and then telling customers "sorry, no fix for you - that product is in extended support" is very poor. If you break something during extended support, you should fix it.