In 2019 classic through mid-WotlK there was also this same exact bug. Rune strike, Bear druid Maul, and Heroic Strike would all cause the Spell Que Window feature that all classes enjoy in WoW to stop working. This was fixed in Wotlk classic.
In Era/SOD, this bug still persists. If you’re on a warrior and you que heroic strike, you can no longer benefit from the Spell Que Window feature in WoW, greatly increasing your GCD timer from 1.5 sec to 1.5 + latency + time-to-press. Easily pushing your GCD into 1.8 second ranges. Over the course of a fight this can push multiple GCDs off.
This bug only happens when your auto is actively qued for heroic strike. It will affect prot warrior the most as you perma-mash heroic strike, so almost every GCD will be delayed. As 2h you still attack pretty fast but sometimes they wont overlap, so only most, but not all, GCDs will be delayed based on heroic strike usage.
To test this bug, take a warrior, go to a dummy (ptr) or any higher health mob/player(duel) and auto attack, then hit sunder armor, wait for GCD to be 80% done, then tap sunder armor again one time and you’ll see it cast right at 1.5 seconds due to the spell que window. Then, try again but make sure heroic strike is qued, and you’ll see that you cannot tap sunder armor once and have it que. You have to wait and press it AFTER the prior GCD is completely over to actually cast sunder again, greatly increasing the GCD timer for you. If your auto-attack heroic strike completes before 1.5 sec it will be harder to test so you’d have to be mashing heroic strike the moment your swing starts again or use a slower weapon to make testing easier.
Because this was fixed in WotLK classic, this can also be fixed in SoD/Era. Devs should find whoever fixed this bug in original classic and get them to fix it in current classic.