Looking for purchasing advice for my next camera.

I sold my 7DII a long time ago and used it semi-professionally for music photography.

As much as I could learn technically, I was suffering in low-light conditions and encountering unwanted noise at lower ISOs. I was running into situations where I wished I had a full frame camera and I really just wanted a new camera.

I enjoyed the A7iii's form factor although once a large lens was attached, it didn't feel as light versus my 7DII. I loved the AF, the tracking speed, and the low-light performance. I also really just loved the feel and general experience and how it felt in my hand. I loved taking it with me and it made me happy shooting with it.

I am seriously considering the a7iii and not the a7R3 because although I enjoy and have printed many of my photos, I don't print that large. I'd be getting 4 more megapixels so would that allow me to print even larger without worrying about quality? The main con for the a7iii is lack of weather sealing. I find myself in poor conditions when shooting outdoors and when traveling and would like the comfort of being able to use my camera in at least light rain.

I am considering purchasing from this gray market (?) seller: https://www.ebay.com/itm/Sony-Alpha-a7-III-Mirrorless-Digital-Camera-Body-Sony-Spare-Battery-ILCE7M3-B/202782564585

I've watched numerous videos on the a7iii in 2020 and it seems like it's still a fantastic purchase to make. I also don't think the a74 will be coming out anytime soon this year.

What are the reasons I should consider the a7R3 over the A7iii?

Thanks for the help!

edit - just wanted to thank you all for the help. it's been great