16 months ago ultra didn't have this lag so one would have to believe it's changes made by Arlo but it has only gotten worse with system upgrades. I wouldn't bet on it getting better. I can't return mine but they will be replaced with something else as they need replacing in time.
Keep in mind the ring isn't 4K, the higher the res the greater wi-fi lag. This doesn't mean Arlo isn't without blame because hardware is one factor. Ex., My brand new Samsung TV has more lag than my Roku. For somethings my wife's iphone 11 has more lag than my10+. If you watch OTA TV on side by side TV's Dish Network's signal has lag, If you stream the same program side by side the stream will have more lag. How it is handled in the cloud is also a area where Arlo may need to improve. If you experiment without a plan you will notice a real improvement in notification speed even though the hub is 4K. You will not however eliminate lag but you should certainly be working on minimizing it as much as possible when your talking a security system. A wired system is the only way to end it completely.