hello i was playing minecraft with my friends on a server i made, everything was good until i put down a gas pump, after that i could see chests and some other things through the wall, i asked my friends if they were also seeing but they said no, i dont know if it is because of optifine.
i still see it after i romoved it.
can someone help me fix it

This is obviously an issue created by a so called "performance mod" which breaks something with vanilla rendering.
If you have any of them installed, both server and client side, you should remove them and try again.

Many duplicate. I'll be going through all issues within the next month

View the issues #446 and #468