I can't save any changes in product in magento 2.3.7 and give me technical problem with server and 406 error in console.
I tried some common solution for which is for that but nothing will help me
this issue only happens when rate limitation rule is applied on server. on save you some time hit button 2 times that mean in few second you tried to hit site again, that mean server thaughts you are robot and disable site for you.
please ask devops guy to check "rate limitation" rule. and either you can ask for disable/edit rule or white list your ip from that rule.
hope it helps!!