I was playing Minecraft (ver 1.20.0) on mobile (iPhone 12 Pro). Long story short, After establishing base on the overworld, I decided to build a nether portal, and then I went in. I successfully built a base there, but I realized something odd in the nether, sometimes when I mine a block, there is a delay for a second or two before the block drops. After some research, I think it was something called tick lag? (still not sure about it). I didn't experience any FPS drop, it's more like a lag when you have bad internet connection, so i guess it's tick lag?? But I'm in a singleplayer, I also turned off multiplayer world in the settings, so internet connection shouldn't be a problem.. right? That's why I'm kinda confused. Another detail to add is that it lags every time I confront ghast, but sometimes it lags too even though I don't confront ghast. FYI, the RandomTickSpeed is set to 1, I can't change it. I recorded a video to make it clearer what exactly I was experiencing.

I can't attach the video because the size is too big, but here is the link to the video. https://www.youtube.com/watch?v=sFTqdP2Cgvs