Is it totally wrong to re-add an ex on social media ?? Your thoughts ??

I’m asking this because I am considering adding an ex back on Instagram but I have had an annoying experience previously and I just want to know what others think ..

Ok so one day I was passing by my ex’s house on a bike with a friend and his mum and sister were standing outside they saw me and waved , I waved back and they wanted me to stop , I didn’t and just waved and told my friend to keep going ..About a week later I saw my ex’s sister’s page on Instagram out of curiosity I checked her profile and then followed her , she followed back and within 24hrs of following her she posted over 10 pictures of her brother ( my ex) , his wife and baby .. I got all the details of my ex’s life since we broke up in less than 24 hrs of following her and it just seemed pathetic to me because I am very sure my ex put her up to it ( it’s the kind of thing he does) but I felt it been like 3 years I mean people grow up and I didn’t expect that and looking back at her previous photos she only had one picture of her brother on her Instagram so this wasn’t normal .. And honestly there was nothing enviable about his life except he has a wife and kid , he still lives with his parents and doesn’t have a job , so I found it really pathetic that after three years he was still trying to prove to me that I lost out on something .. it was all just annoying and I think I unfollowed her ..
Recently been thinking of following back another ex who I broke up with because he cheated on me , we have talked since then and met up twice after the break up , thought of him recently and checked his Instagram I noticed he never unfollowed me even when I unfollowed him but now I want to follow him again , not because I want him back or anything but because I feel enough time has passed and all that happened is behind me now and we can at least be friends online ..

With my most recent ex even if things ended badly I know in maybe a year from now I would probably want to add him back on Instagram or something because again , I have moved on , all the anger and resentment would have gone and enough time would have passed ..

Also i have had ex’s add me back even a few months after the break up and I don’t feel when an ex adds me back it means they still have feelings for me or want me back , I know people move on and they probably added me again out of curiosity as I do and it usually just the same thing as when any other person I know sends a friend request .

So is it totally wrong to add an ex back on social media after sometime or do they automatically assume you want them back or still have feelings for them when you do so ??