Don't worry, your world isn't beginning to be corrupted. This happens to every world, it's normal for the world file to increase or decrease by a few megabytes depending on what happened the last time you played
Have you checked the light levels to make sure it's not just grass deteriorating? Grass will turn back into dirt under blocks like fences if there isn't sufficient light
Affects 1.14.20 Hotfix on Windows 10
When crafting firework stars into rockets, using only one firework star with effects (mob head, fire charge, diamond, glowstone), the crafted rocket will not have any effects and will only keep the star color. If you use two firework stars, the crafted firework rocket will keep all its effects.
Affects 1.9.0
sometimes end gateways are badly generated and will drop you into the void when you try to ender pearl through. you're unlucky cause it seems like your only gateway is messed up, but try killing the dragon and spawning another gateway, it should work just fine
Active on 1.2.0 though the bug has gotten progressively better. Most items are now fine, as well as placed chests and ender chests. I haven't looked through the textures extensively, but glass, plants, and redstone are still most noticeably messed up. Glass has gotten better, it now shows a faint outline of the texture instead of only the 4 corner pixels.
Still happens on 1.1.5 though things have gotten better. When I tried it right after the nether blocks update, magma blocks were 8x8 on a 32x32 texture pack and the inventory icon was bad. Now, most inventory icons including glass are fixed, except plants still have the white blurring artifact. Most blocks are still blurred to 16x16 when placed.
Don't submit 2 bugs in the same issue
Still an issue in 1.14.30, gives me the error number -9