As a child from this situation (younger mum though) I can’t say it was bad for me - stressful and difficult for my mum though! I was raised knowing he was a spermk donor and never wanted a dad, sometimes I did want to be ‘normal’ but I was fine with not having w dad as it’s all I’ve ever known. With that said I was raised alongside many children from single parent families (I was the only sperm donor kid though!).
If someone told me they could give me the identity of my sperm donor, I wouldn’t want to know - i don’t see him as a father, or even ‘real’ exactly (although I’m grateful that the mystery man donated). But I was born post 1991 (creation of the register) and pre 2005 (obviously). Children born now will have more information available to them - in a way it was easier for me because I knew when I turned 18 that there’s little information even I requested it (I haven’t requested further information).
I think for me the fact I came from sperm donation became irrelevant quickly. I was told since I was a toddler. I’ve never thought I shouldn’t have been born because, as with most people, the facts surrounding their conception becomes history the moment you’re born: you live as w single parent family, I’ve never faced stigma for that, people are used to different families etc.
I do think it would have been easier for my mum to have a second parent so when she was stressed or exhausted or ill, there’d be a helping hand - but that could have been fulfilled by being rich enough to afford a childminder or a nanny lol.
I’d be hesitant if you lived in an area where there might be stigma. Every child I met growing up accepted I didn’t have a dad, that was the only explanation needed. There was no Father’s Day events at school anyway, and if I got asked about my family I didn’t ever worry about saying I didn’t have a dad etc. I wasn’t a confident child in general, it wasn’t about confidence - it just didn’t merit any interest, embarrassment etc full stop and by the time i was a teenager and it could’ve, I was in an area where there were several single parent or divorced families so no one would have asked questions. If you live in an area where your child is going to get intrusive questions and stand out, it might be different however, and could be quite difficult for them.