Why is 00:00:00:00:00:00 address used instead of broadcast address ff:ff:ff:ff:ff:ff in ARP?

The following is my stripped down ARP ruleset, only broadcast rules are shown, other rules (not shown here) are not relevant. Please see code comments that are questions (?)

#!/usr/sbin/nft -f

add chain arp arp_table input {
	# filter = 0
	# Packets delivered to the local system
	type filter hook input priority filter; policy drop;
}

add chain arp arp_table output {
	# filter = 0
	# Packets send by the local system
	type filter hook output priority filter; policy drop;
}

# ARP Broadcast address
define broadcast_ether = { ff:ff:ff:ff:ff:ff }

# IPv4 network address
define network_addr_4 = { 192.168.1.0/24 }

# NIC ether address
define physical_ether = { bb:c9:51:d4:4a:b6 }

# Why input to broadcast address never hits?
# This rule should handle broadcast input
add rule arp arp_table input arp daddr ether $broadcast_ether log prefix "ACCEPT input broadcast: " accept

# Why input to 00:00:00:00:00:00 hits instead?
# This rule handles input toward 00:00:00:00:00:00 from LAN
add rule arp arp_table input arp saddr ip $network_addr_4 arp daddr ether 00:00:00:00:00:00 accept

# Why output to broadcast never hits?
# This rule should handle output toward ff:ff:ff:ff:ff:ff to LAN
add rule arp arp_table output arp daddr ether $broadcast_ether log prefix "ACCEPT output broadcast: " accept

# Why output to 00:00:00:00:00:00 hits instead?
# This rule handles output toward 00:00:00:00:00:00 to LAN
add rule arp arp_table output arp saddr ether $physical_ether arp daddr ether 00:00:00:00:00:00 accept

There are several questions here, the main one being that ARP broadcast traffic ff:ff:ff:ff:ff:ff is nonexistent, that's why I added log statement to hopefully catch such traffic but it never appears, for both input and output traffic. What happens instead is I see a lot of intput/output directed toward 00:00:00:00:00:00 address, which suggests that 00:00:00:00:00:00 is broadcast address somehow. So the main question is why don't I see ARP traffic directed toward broadcast address and why is 00:00:00:00:00:00 address used instead? 2nd question is, what is 00:00:00:00:00:00 address? why it is needed and what does it mean? If I block traffic to/from 00:00:00:00:00:00 (ex. by removing those rules) then networking will stop to function due to a such ARP packets being dropped.