So, I have bad news. But after that, some good news!
First the bad:
Back in 2015 Ikea discontinued the older AKURUM kitchen system, and replaced it with the current SEKTION system.
It looks like your kitchen was built before 2015, because those are AKURUM cabinets - you can tell because yours only have a single front line of holes, compared to the double lines of holes on SEKTION:
Sadly, although the newer shelves made for SEKTION can physically fit in your cabinets, the rear peg holes would not line up.
But never fear! I have a solution!
Head down to your local Home Depot and find something like this:
https://www.homedepot.ca/product/columbia-forest-products-5-8-in-x-15-3-4-in-x-96-in-smarttop-shelvi... and some of these: https://www.homedepot.ca/product/richelieu--pack-of-8-3-16-in-5-mm-metal-shelf-pin-nickel/1001066216
Then head to the panel saw in the back corner of the store with your board and measurements, and you can ask an associate to cut your shelves to size.
It won't be quite stock-looking - these Home Depot shelves won't have the nice recessed/hidden pegs of the originals, and the white colour may not be identical (you can bring one of your existing shelves to the Home Depot to try and and colour-match though!) - but they'll be close enough that you probably won't notice after a few days.