If the universe has infinite value, and no action can increase or decrease the value of the universe, think locally: What can I do to reduce the value of the universe in ways that do not affect agents (Since that is the only way to increase the value in ways that do affect agents.); conversely, act to maximize value within your own cosmological event horizon, knowing that this results in harm only to entities that cannot ever be affected by you. (Zero sum, right?)
Oh, and the entire thing begs the question of ethical consequentialism. If I reject general consequentialism because I refuse any ethical system that requires me to kill people, then most of the questions become null.
I don't think that's quite how infinities work. If we posit that the raw universe as a whole including beyond any event horizons is infinite in spacetime size, then you can't change the total value of the universe ("Infinite", considering at least 1 of the smallest unit of value per largest unit of spacetime) while still massively increasing your local value, without stealing it from anywhere.
The original wording and question are ambiguous anyway. I wish that "infinite value" were taboo'd.
Will Crouch has written up a list of the most important unsolved problems in ethics:
The Practical List
What’s the optimal career choice? Professional philanthropy, influencing, research, or something more common-sensically virtuous?
What’s the optimal donation area? Development charities? Animal welfare charities? Extinction risk mitigation charities? Meta-charities? Or investing the money and donating later?
What are the highest leverage political policies? Libertarian paternalism? Prediction markets? Cruelty taxes, such as taxes on caged hens; luxury taxes?
What are the highest value areas of research? Tropical medicine? Artificial intelligence? Economic cost-effectiveness analysis? Moral philosophy?
Given our best ethical theories (or best credence distribution in ethical theories), what’s the biggest problem we currently face?
The Theoretical List
What’s the correct population ethics? How should we value future people compared with present people? Do people have diminishing marginal value?
Should we maximise expected value when it comes to small probabilities of huge amounts of value? If not, what should we do instead?
How should we respond to the possibility of creating infinite value (or disvalue)? Should that consideration swamp all others? If not, why not?
How should we respond to the possibility that the universe actually has infinite value? Does it mean that we have no reason to do any action (because we don’t increase the sum total of value in the world)? Or does this possibility refute aggregative consequentialism?
How should we accommodate moral uncertainty? Should we apply expected utility theory? If so, how do we make intertheoretic value comparisons? Does this mean that some high-stakes theories should dominate our moral thinking, even if we assign them low credence?
How should intuitions weigh against theoretical virtues in normative ethics? Is common-sense ethics roughly correct? Or should we prefer simpler moral theories?
Should we prioritise the prevention of human wrongs over the alleviation of naturally caused suffering? If so, by how much?
What sorts of entities have moral value? Humans, presumably. But what about non-human animals? Insects? The natural environment? Artificial intelligence?
What additional items should be on these lists?