What r/sudoku is talking about this week

Okay so I'm a beginner at sudoku and I've been staring at this puzzle for the past 10 mins and can't figure out and I also looked at the solution but it doesn't explain so I don't need the answers...

or is this what they call the finned y-wing? like i was pretty sure i could eliminate the 9 in the blue cell. r4c5, r4c6, and r9c6 form a xyz wing. but there's nothing that can be eliminated. but...

I started 2\~ months ago and on the Sudoku.com app I can finish the extreme levels, although it takes me 10-15 minutes. I previously only did it online only but I got a book of it and I spend...

I'm sure it's obvious. But it never takes me this long.

This sudoku has me stumped. The upper diamond shape is a region sum line in which each region has a value between 15 and 17, the orange semi circle surrounding the 9 is and entropic line. It has...

I was playing "petdoku" where you have to place a cat in each row, column and color (region) and I was stuck so I used a tip and got this. Is there an equivalent to this trick/rule in sudoku? I...

By elimination applied on columns 7 & 8, I know that R6C9 is NOT a 1, therefore it's a 6. But is this a standard technique that I don't know of?

Don‘t really know much advanced techniques, so I’m stuck here