This is well-documented, though I don’t know for certain when it became the norm.

If you go back to the 1999 Seattle WTO protests, you mostly see people using short, concealable weapons, such as wooden clubs.

At some point, the gear of choice evolved towards the plausibly deniable, including skateboards, umbrellas, etc.

2020 example:

https://mobile.twitter.com/TheGunzShow/status/12668514068222...