One of the new additions many players were looking forward to in Shadowlands patch 9.1.5 was the ability to easily solo old Legion legacy raids, but as many players are reporting, many are still not achievable, mainly Tomb of Sargeras.
The final two bosses, Fallen Avatar and Kil'jaeden are still DPS checks, and taking players upwards of a few minutes to attempt to take down.
Many players are frustrated as Warlords of Draenor, the expansion before Legion has higher scaling damage multiplayer once inside, and takes longer for players to defeat each boss, despite both expansions classified as "legacy content".
Legion Legacy Raids Are Still Tough For Players To Solo After Patch 9.1.5
It is likely that with more gear and as the expansion goes on that these raids will become simple to solo, although players just wish all raids scaled the same, as there is no player power benefit to running old raids, people just want to farm old gear sets and rare mounts.
Mechanically, these fights weren't meant to be completed solo, which is where higher scaling would benefit these fights.
An encounter such as Kil'jaeden has a phase where he is invulnerable for minutes at a time, and players lacking self-healing are reporting they are just dying and failing.
Hopefully, Blizzard make adjustments to these encounters soon and let people begin farming their desired raids without needing to endure long encounters that are from 5-year-old content.