This is not a technical problem. Try to find out who is accountable. Who gets fired when the software doesn't perform the way it should. Notice nobody gets fired. Because the whole chain of command is afraid of accountability for themselves.
And so, everything from Hollywood blockbusters to software solutions is created by committee. The end products are all box-checking, lowest common denominator throwaway garbage. No risks are taken. And very little value is delivered.
You need power to exercice accountability. Otherwise anybody can come shit in your codebase, and you are now accountable for it. Because you do not have the power to refuse the turd.
And the company probably pays a platform team to offer a limited but supported tech stack.
The platform team is accountable for balancing the deprecation of outdated dependencies and the productivity of their users.
Either decision could easily be justifiable. The higher ups may have deliberately wanted to assure the teams were not stifled, or a team may have had a goal which demanded an exception to the rule. Still though, somebody had to have made the call and should therefore be able to justify it.
If an organization does not know who is responsible for something, then that is a failing at an even higher level.