crash after ~30 minutes of playing & gaps between blocks

I have been playing snapshot 20w07a just looking at the new stuff and it just for no reason crashes after 30 minutes have two log files attached never crashed before 20 minutes
what i was  doing when the first crash happend i was mining a path in the nether an it crashed
the second crash i had my game on the background while standing in a warped forest after i had build a few walls (nether brick)

For the gaps i have attached a screenshot overworld only (affected in multiple version)