We have to be in n the office 3-days so if I WFH because sick, I would have to badge in Friday. This is foolish so I take a sick day if I’m not going into the office.

That doesn't work for a lot of people due to workload, but that is a separate problem

True. I can’t take RTO organizations seriously about productivity

Huh; my org seems to be pretty lenient in that regard - if you are ill or book time off on a day you meant to be in the office it's fine.

My org may be more lenient than I understand it to be, mainly I don't know what if any consequences there are if I do WFH while sick/recovering/contagious and am only in the office twice in a week.

If you are happy about your relationship with work such that you would prefer to do it rather than rest, then what I have to say next is not relevant to you. For others whom this might not be the case: You need rest. If your only or primary form of rest is Netflix on the couch, such that you feel you “should” work instead, you might consider if other forms of rest might be better for you.

Rest benefits you and your employer. Working while ill is a sure path to burnout. Burnt out employees are less productive and more likely to quit.

It’s okay to not grind 25/8.

It's my personal preference and it has worked for me in the last 25 years, but everybody's different and it might not work for everybody.

Note that doing nothing does not necessarily mean that you relax. Working at home at your own moderate pace might make you recover faster. But again, what works well for somebody might not work well for someone else.