Product Owner suddenly sick before a sprint review

A Product Owner should always have someone identified who can act as a "proxy" product owner when needed.

Could the Development Team vote for one of them to take the voice of the team with the stakeholders?

Yes, they might decide amongst themselves to provide stakeholders with this option. That would be one approach a self-organizing team might take.

If PO or a representative/proxy is not present in sprint review meeting then the meeting should be rescheduled to when PO is available.

Thank you for the answers.

I think the team always has to agree on a strategy in the event of the PO's sudden absence. The worst approach is rescheduling the meeting because of the consistency and pace lost, also, you'd need to have the meeting days after, with the consequent problem of sprint duration and coordination with other teams.

Sorry for any mistakes. English is not my native language

This is an informal meeting, not a status meeting, and the presentation of the Increment is intended to elicit feedback and foster collaboration.

Is the absence of the Product Owner preventing the Scrum Team to gather feedback from the Increment? New items might raise and would be discussed when the PO will get back as he is the sole person responsible for managing the Product Backlog (Scrum Guide).

New items might raise and would be discussed when the PO will get back as he is the sole person responsible for managing the Product Backlog (Scrum Guide).

Below this, the Scrum Guide says:

The Product Owner may do the above work, or have the Development Team do it. However, the Product Owner remains accountable.

I think it is valid that the rest of the Scrum Team find a way to inspect and adapt to new information even if the Product Owner is absent. A wise Product Owner would perhaps empower the team to be able to handle this circumstance.