https://github.com/JamminL/wotlk-classic-bugs/issues/182 was fixed for Wrath, introduced with TBC (which is why it was introduced into the SoM client, because they ran the same architecture and this bug wasn't present in 2019-2021.)
NOTE: This is working as intended on the PTR, but just for clarity in case it bugs again
1. Current Behavior
1.1. Description
Vanish doesn't remove combat in Battlegrounds
1.2. How to Reproduce
1.3 Source Material
https://gyazo.com/01efb2979c9c21facae633eed269cafc
2. Expected Behavior
2.1. Description
Vanish should remove combat in BGs/instanced PVP
2.2 Source Material
https://github.com/JamminL/wotlk-classic-bugs/issues/182 was fixed for Wrath, introduced with TBC (which is why it was introduced into the SoM client, because they ran the same architecture and this bug wasn't present in 2019-2021.)
NOTE: This is working as intended on the PTR, but just for clarity in case it bugs again