Write up the eval with the issues you see and submit it to your manager by the “eval due” date.
Do NOT go over their heads to HR, you’ll be out of there at their next opportunity.
But also do not accede to any requests to change the feedback. “This is the big problem I see. You may be willing to change it or not, that’s not my problem, but this is why people quit the job, they get bait and switchesswitched into an unacceptable work-life balance due to the oncall.”
Then it is your manager’s job to pass it on or redact it or whatever, you’ve done your job.
If there is follow up where HR or anyone asks you, be honest and say “it’s the oncall.” If it gets to “why want they mentioned in the eval sent to us and/or why has nothing been done about it” you say “I’m sure I wouldn’t know.”
The trick here is to do your job responsibly without either becoming a collaborator in your boss’ misguided attempt to hide a problem or deliberately usurping their authority. Be honest but stay in your lane. You can always choose to leave a job, but much of the advice here will necessitate it for no better outcome.