1 GB is a big bottleneck.
2 GB is a bit of a bottleneck, but it’s not bad.
3 GB isn’t a real bottleneck for most usage in my experience but that’s in 2019. Who knows in 2021 though? Also, in my case I wanted to try dabbling in some video editing and I figure it’d be better to have more RAM than less, especially since Apple already sets the Pros at a mininum of 4 GB but allow you to buy up to 6 GB RAM.
It seems that when Apple sets a baseline in iOS, that baseline starts to become a bottleneck in a few years even just with regular consumer type usage, not just more complex stuff like video editing. The other thing is that the machines with less memory seem more prone to weird behaviour like random software crashes, although this is just anecdotal. It should be noted that no iDevice that came out after the release of iOS 12 has shipped with less than 3 GB, so Apple has set its new baseline now at 3 GB... even for the iPad mini.
In this scenario, with the 10.5” iPads, we were presented with a dilemma. Either buy an Air with 3 GB RAM and a bunch of missing features, or else buy a Pro that came out two years ago meaning it will likely be updated for maybe 1 year less (or worst case scenario, two years less), but with 4 GB RAM and which has a bunch of really nice features like ProMotion and quad speakers. I struggled with this decision for a while, but then I figured I’d probably upgrade in 2022-2023 anyway, which is about when the iPad Pro 10.5” might stop getting iOS updates. In the meantime though, I’d get to enjoy the extra features, and would have the extra RAM just in case I need it for stuff like video editing apps. As mentioned, at least anecdotally it seems machines with less memory sometimes can cause random software crashes more, so having the 1 extra GB might actually help in more complex usage. I’m not just talking about tab reloads here anymore.
The other thing to remember is that typically with iOS, apps usually support versions about 2-3 years old, even as they continue to become more complex. So even if a 10.5” Pro were to lose iOS updates in 2022, it would still remain a viable machine in 2024 in terms of software support. I would be shocked if by 2024, 4 GB wasn’t Apple’s chosen minimum RAM configuration.