
TBC Anniversary loses 88,000 raiders in the first beta week
TBC Anniversary lost 88,334 raiders in the week the World of Warcraft: Forever beta opened. The count fell from 212,821 to 124,487, according to Ironforge.pro, which reads the logs of Warcraft Logs. MoP Classic dropped by a quarter.
TBC Anniversary
Ironforge.pro counted 212,821 raiders in TBC Anniversary from 8 to 14 September. From 15 to 21 September there were 124,487, a drop of 41 percent. The Forever beta opened on 17 September, in the middle of that second week.
Forever only launches on 4 November, and guaranteed beta access comes with the Skyborne Epic Pack for 59.99 euro. So TBC Anniversary was expected to keep a strong raid population until the launch.

The chart also shows that the decline started earlier. At the peak in May, more than 320,000 players raided in a single week. In the week of the beta, Alliance and Horde were almost even: 60,689 against 63,798.
TBC Anniversary is in phase 3, with Black Temple and Hyjal Summit. Zul’Aman and Sunwell Plateau are still to come. Whether Wrath of the Lich King Anniversary follows after that is not known.
MoP Classic
In MoP Classic the raid population fell from 33,125 to 24,971 in the same two weeks, according to Ironforge.pro. That version has been in its final phase since June, when Siege of Orgrimmar opened.

Players of MoP Classic are waiting to hear what happens to their characters. Many have played them since WoW Classic launched in August 2019. What Blizzard plans for them has not been announced.
What the figures do not show
Ironforge.pro only counts raiders who appear in logs on Warcraft Logs. Raids that nobody logs are missing from the count.
The drop most likely means players who are either in the Forever beta or waiting for Blizzard’s plans for both versions. Whether the raiders come back after the beta is not known.
Source: Wowhead