They aren't scarce they are way more common than in BotW. But you are also more likely to use them a lot in this game compared to BotW.9

Arrows are very common in TOTK even on the low end of drops you can easily have 30 to 50 in stock. 

I finished BOTW in February with over 150 in stock, this time less than 50 despite more or less completing the same amount of tasks and buying far more from Beedle. Huge difference considering I wasn't even using them to shoot glowing seeds or w/e.

Maybe there's more scattered around the overworld, IDK, but I have no patience for open-world collect-a-thons.

Yeah I've noticed that there's almost always arrows inside crates and such, but just in general arrows are way more scarce than in BotW because well, they simply are. In BotW you'd buy arrows, fire arrows, shock arrows, ice arrows, bomb arrows (was easier to get money for all of them too) and then you'd use each of them in different moments, but now all you get is regular arrows in the same amount as you used to. So there's just less of them.

Also is it just me, or has bow durability in general been nerfed?

That’s the thing for me, I have never had more than 70 arrows in TotK and I have ran out on several occations. And I forage all that I can. Also so far I’ve not been able to afford/prioritiezed to buy them in shops.

But as I said earlier, it might also be that I have a slightly different play style than BotW (it’s been a while since I last played BotW). 

I've not done any collectathons and found way more arrows than in the prior game the only reason my stock is often around 40 or so is because of the frequent use of them. They're dropped so often from crates, barrels and enemies to the point they're far more common than in BOTW. Most chests will even contain them, to say they're scarce in the game is objectively incorrect even in comparison to the previous game at the very minimum it's on par. 

Yeah there's a few more regular arrows to find than in BotW but like I said the reason why they feel more scarce is because you don't get an extra supply of fire/ice/shock/bomb arrows on top of them, so you just end up using way more of the normal arrows.

The is a lot more than a few more regular arrows in drops even when you account for the other arrow types in BOTW for example one of the Temple/Dungeons has several chests with bundles of 5 and 10. The are also a lot of enemies in the game armed with bows who often drop arrows up to the range of 5.

TOTK I am finding myself using the bow way way more but my average stock is remaining around 40 to 50 which highlights how ridiculously common they've become considering how much stronger archery has become in TOTK, the are points it's almost overpowered. 

I mean, my "average stock" in BotW was usually over 100 (and then all the other arrow types), so

My arrow stock hasn't gone below 300 since the tutorial area after at least 70 hours. The maximum I had was just over 600 arrows. And I use them for almost everything. I collect the arrows that enemies shoot, arrows in boxes, in barrelsand in chests, arrows that enemies drop when they die etc. I also try to always retrieve all arrows that I miss with if I can. No arrow goes to waste.

I never buy arrows in TotK since rupees are harder to come by. In BotW I'd constantly buy arrows, that was my main source of normal arrows in that game. I always had 100-150 of each arrow type except for bomb arrows which I had maybe between 50 and 100 of.