Should I contact my grandparents for their birthdays (no contact, on bad terms)

So my parents and I have gone no contact with my grandparents (my moms side) for almost a year because they have been repeatedly treating my mom like shit for multiple years without ever realizing what they were doing to her mentally ( I don’t really want to go into detail but it was really bad).

Finally my mom snapped and abruptly broke off all contact with them. The last time I spoke to them was my grandpas birthday about 8-9 months ago (I only called because they called me for my birthday 2 weeks prior). Since then I also haven’t spoken to them. Since I witnessed everything that was happening I knew what I would stand by my mom’s side.

Since then we haven’t spoken at all. I graduated, got my drivers license, started university and all the holidays since then.

From my uncles who still talk to them, I found out that they don’t even know why my mom and I stopped talking to them and that they were especially disappointed that I also don’t talk to them anymore.

Now my grandmas birthday is coming up and I don’t know if I should at least wish her a happy birthday, I probably shouldn’t, especially since they are incapable of recognizing their own mistakes and by sending her a message I’d probably feed into their delusion that they aren’t at fault and that it’s all my mom and I.

What should I do?