too much lag and very unstable

everything around me is slow such as mobs movement , they move and pause for a second and move again and if i attack them the mobs react after a second and even if my wifi is perfectly fine i am suddenly not able to interact with the world,im not able to see breaking animation and im not able to collect the block and then im only able to see chunks in my render distance and when i go to the end of it its completely empty and i cant open any ui like my inventory or the crafting table but i reported this before and it was resolved but now it started happening again and if you want to actually understand this issue you can join a realm and then switch off the wifi and try playing and thats what i experience with perfectly fine wifi because im able to watch youtube and other things