I copied my existing 1.17 world into the latest beta. Note: The world has existed since 1.13. The copy opens but I quickly notice that I cannot mine place or interact with blocks properly. When I try to mine the block disappears without sound or particles and the block will reappear after a minute or so. I can enter the space where that block used to be but if I am in the space occupied by the block when it reappears I will start to drown. If I try to place something in the space the missing block will almost immediately reappear instead of waiting. I cannot usually place an object anywhere but I’ve found that if I spam the place button it will sometimes work. It is difficult to interact with chests or blocks such as the crafting table; trying to usually results in nothing happening. Please note: I did not remember experiencing any of these issues prior to 1.18.0.25 when I made test upgrades of my old world.

I did find the block lag went away once when I ‘mined’ into a deep slate cave and moved around attempting to place torches. The way I came in had sealed back up but for a few minutes I was able to move  place and mine like normal. Eventually however the block lag returned and no amount of spamming the torch placement seemed to work.