As someone who routinely plays with strangers, I don't think this will be an issue. You simply state up front which rule set you are using and if you are ok with mixing and matching and what you are mixing and matching. So, someone wants to use a 2014 monk (as a totally random example) might be perfectly fine, but the DM, before the game starts, simply says, "2024 spells take precedent". It's not like it's a major hurdle here.
Sure, there might be the odd rough patch here and there, but, again, I've been instituting Tasha's changes for a couple of years now and no one seems too terribly fussed about it.