Even if 2.4 does make changes that might cause problems for customisation, that is fine. It’s not like as soon as 2.4 drops that you should update.
Stage that update, make fixes then push to production when ready.
We also don’t have details on what exactly is being changed. Only that x, y and a features are being updated or added.
But that’s not the point, I think you skipped over my question completely. What’s stopping you? I personally see no reason to stop changes being made by me on 2.3, the only time I’ll slow down is when 2.4 so I can focus on updating my changes. But even then I’ll be carrying on with any patches that need creating to my current content until I’m fully ready to make that upgrade.