I used to think work from home have lots of pro like we can save our travel time, don't need to dress-up etc and I always wanted to do wfh. But this Covid-19 pandemic made me to hate work from home now I want to go back to office so that I have fix in-time and out-time and proper 8 hr work time.

Same, but mostly just because kids...

I don't want to go back to the office, just want my space back.

Yeah, Covid ruined my perfectly sane job schedule.
Now I'm in search...

Just keep the same strict times when wfh?

Yeah exactly this. Although I must say that it helped when I recently agreed with my partner that we'd both ignore each other as if we'd not be home when working from home. It's just way too easy to distract each other. Especially in a single room.. Of course we still interact sometimes or get each other drinks/food. But it wouldn't be more distraction than what I'd have on the office.
And yeah it's a great tip to try and stick to normal office hours, helps somewhat for me