I have two shiny Pokemon experiences from playing through Shield.
When I saw a Pokemon, I made sure to get a good look at it in case it was shiny and even ran into a few that were close in color just to be sure. On Route 3, when I saw the new Pokemon Sizzilpede I thought it was interesting that its back looked green. Later in the Fire Gym my heart sunk when I saw one that clearly had a brown back and didn't sparkle. After I stopped playing for the day I checked to see what shiny Sizzilpede looked like and guess what color the back was. I thought I'd seen it in the overworld and not ran into it because I didn't realize it was shiny at the time, but later I found out Sizzilpede don't even appear in the overworld. A trainer had one and I couldn't tell the back's color because of the glossy glare covering most of it. Long story short, I'm paranoid about Shinies.
After getting the final badge, I ran around some places with water to find what was hidden there and on Route 2 I saw a gold aura Rookidee. (Gold aura means it has an Egg Move, earns you Watts if you catch it, and I think it also means it has have 3 perfect IVs) Watts are a thing that you really should take when given the opportunity, so I ran into it and it was yellow! It was Blue in the overworld. (which makes my paranoia even better in hindsight) I was so shocked I didn't even pay attention to the Shiny Sparkle, but I did know it was an improvement over Gen 7's giant star. I'd checked what Shiny Corviknight looked like before so I knew the Heavy Ball was the best match. I thought a moment about what the catch rate might be and figured it would be pretty much guarantee if I lowered the health some. When it used the Egg Move Roost, I thought, "Sweet, I'm using Toxic!" Anyway, it was perfect luck. I ran into a Shiny, had a way to not KO it even though my team was around Level 50 and it was Level 7, and it even had the Egg Move I wanted. I'd done a few raids, so I could get it to Level 40 with candies. (It replaced Dubwool on my team. Sorry, Wooloo's less cute after evolution.) When I paid attention to the Gen 8 Shiny Sparkle I thought it looked kind of weird. It looked good with the Heavy Ball's release animation, but I didn't get why the second half of the animation had square sparkles. The next morning I checked Serebii, saw it had a SwSh page on Shiny Pokemon mechanics, and it said that one in sixteen shiny Pokemon had a Square Sparkle instead of Stars. (It's glitched with shaking grass, fishing, and I think berry trees, so Shinies from those are almost always Square.) It was a full odds Shiny and a one in sixteen "super shiny" The odds of that are 1/65,536! If you also count that it had the best of 7 Egg Moves in the odds, then its 1/458,752... Holy ****ing ****...
Just caught a Shiny Snorunt today while looking for a Honedge (and yes I did catch a Honedge a few minutes later)! :)
Are you evolving it into Frosslass or Glalie if you have the choice, are the sparkles stars or squares, (if squares, was it from shaking grass?) and did we switch accounts or something? You made a one line post and I made a wall of text... :P