kinda long

I 23F and my sister 16F are in separate states due to me moving out. I promise this is relevant. We're not super close due to age gap but we get along pretty well.

It was her birthday recently, and my mom reminded me that it was her birthday and I needed to call her to wish her "happy birthday".

Now, I believe birthday calls are stupid. I personally think they are the most fake, most rehearsed, and non genuine thing to do. I'd rather text and allow them to respond at their own pace, since it's THEIR birthday and usually they have things going on.

Anyway, I told my mom I would call (a lie, but I wasn't going to explain my reasoning to someone who's already said my view is garbage and rude) instead, I texted my sister, wished her happy birthday. Which my sister replied a few minutes later saying thank you, and she thanked me for a virtual gift I had sent her earlier. We messaged back and forth laughing and joking around. All was well.

Well, apparently not. My mom messages me the next morning saying how 'appalled' she was by my behaviour. How 'typically rude' I was by not calling. And how 'visibly disappointed' my sister was because of it. Which confused the hell out of me. I texted my sister asking if she was upset that I didn't call, she says no. She has the exact same viewpoint on birthday calls as me.

So essentially my mom lied to me just to make me feel bad about not doing what she told me to. So I confronted her. This is our exact text conversation.

Me: "You know her and I are on the same page about birthday phone calls?"

Mom: "If that's the case I wonder why she was disappointed..."

Me: "Oh was she?"

Mom: "I asked if she'd heard from you before we left to go out to for dinner and she said no. She didn't make a big deal out of it, just looked disappointed and surprised. I would not have asked her but as I reminded you twice and you said you were going to call her I assumed you would have. Imagine how you would feel if your birthday came and went and no one called or messaged you? Probably not very nice."

Me: "That's kinda rubbed me the wrong way, no need to get examples involved in case I forgot to use empathy for my sisters birthday. I contacted her all the same, and we laugh now about how silly the whole thing was. You making me worried I'd hurt my sisters feelings when in reality I didn't."

Mom: "You weren't worried or you would not have done that. So I'm not the least bit concerned if it rubbed you the wrong way. So typical of you to not take any responsibility for your actions. Now you've turned this into something it needn't be. You asked if I was still angry and I said no. Sienna was laughing about your messages so she was fine and then so was I."

Me: "Far out, you say some odd things sometimes."

Mom: "🤣🤣🤣🤣🙄🙄"

And that was it. I'm not sure what to make of it but my sister and I both think she's mad about something unrelated and took it out on me (which she does regularly) or is she in the right?

** EDIT **

Just a quick recap in case people are just skimming over this, lied to mom about calling my sister, texted her instead, mum lies to me saying my sister was super upset I didn't call, I asked my sister and she denies it. She agrees that birthday calls are stupid