Found out on Facebook first

[Chickenfingers]

I started a new business, nothing big, just art stuff on Etsy, I'd intended on rolling out after new year, I had a change of mind and working until early mornings to see if I cash in on Christmas (worth a try!) And rushed it out this morning.
My dad is annoyed I didn't tell him first. I'm in my 30s, we speak maybe every 2 weeks and not seen eachother for months as I'm in tier 3.

Aibu to think i shouldn't have to tell him first? I've been stressed enough with a baby and also doing this, on top of going through redundancy, the last thing I expected was to be told he was upset I didnt tell him first like I'm a child.

It sounds like he is reacting differently because he is feeling lonely/isolated, and this is lockdown getting him like you say.
But it's quite manipulative and avoids him having to acknowledge that the issue is his feeling isolated and wanting you to visit/call more often. You don't have to announce these little things to your parents, and not doing so doesn't make you a bad person.
Good luck with your Etsy outlet, hopefully you can give him a call with some really good news following a successful launch and few weeks of busy trading!