In this video I think it's demonstrated incredibly powerfully what importance needs to be placed upon anti-horse tools.
The horses do the bulk of the work in creating space that allows the police line to tighten the noose here. Without them they never would have controlled these crowds with people on multiple sides of them. They could not have maintained control.
There must be simply and effective methods to spook these horses without causing a danger to them. Something that could be deployed that would make the riders tell their superiors "we can't deploy because the horses would be spooked by x".
Anyway. What are other people's thoughts here? Obviously this protest was unprepared for a fight (although several police have been hospitalised). What could small groups of 1-5 have done in the wider engagement to make things go differently?
Lets see, concertina/razor wire or any mobility-inhibiting ground devices such as mass steel ball bearings if you're on hard surfaces or mass three by three by three potholes as well if you're in soft terrain and have enough prep time. Simply using ropes to entangle the calvary legs or to create an anti-calvary barrier is good as well.
Solid blunt bludgeoning objects are always good as well. They're not just useful for incapacitating or dismounting the rider but in desperate circumstances easily allow the wielder to break the knee joints of a horse permanently crippling it's ability to assault your forces and opens the rider injury from being pinned to the ground by the fallen horse.
If you're looking to create an impromptu anti-calvary barrier, a barrage of molotov cocktails in front of moving or charging mounted infantry can frighten the horse from approaching, and should they be timed right frighten the horse into bucking backwards and dismounting their rider. Alternatively utilizing knee-height or higher objects to form a barricade is effective at breaking the mobility of calvary on open ground, forcing them to either waste time maneuvering around it or relying on ground infantry to move in to clear a path.
Classically stone-throwing if no other resources are on hand is always a good tool to motivate horsemen being used to corral your group in to keep their distance.
Of course being in America, doing any of these actions opens you up to being shot to death for trying to defend yourself from being trampled to death - so the best defense here in a stateside protest is thr disciplined wielding of firearms in self-defense against the State. I'm sure any pigs on horses that fancy themselves as the modern dragoon or hussar are well aware of why nobody uses horses in warfare anymore.
You can also smack a horse behind its front leg joints to make them fold and drop to its front "knees". Might get lucky and watch the rider go flying over the top.
Hm that'd probably be easier in the situation the Bristolians found themselves in with the police calvary primarily being used as a herding mechanism.