Same issue here with missing ActivityLog table: 
Running Jellyfin on docker/Linux (Synology NAS), latest "original" image (image: jellyfin/jellyfin)
Running Jellyfin on docker/Linux (Synology NAS), latest "original" image (image: jellyfin/jellyfin)Code:
2025-10-20 16:35:49.157 +02:00] [INF] [9] InternalCodeMigration: Perform migration "20250420070000_MigrateActivityLogDb"
[2025-10-20 16:35:49.167 +02:00] [WRN] [9] Jellyfin.Server.Migrations.Routines.MigrateActivityLogDb: Migrating the activity database may take a while, do not stop Jellyfin.
[2025-10-20 16:35:49.875 +02:00] [FTL] [9] InternalCodeMigration: Error: "SQLite Error 1: 'no such table: ActivityLog'."
[2025-10-20 16:35:49.875 +02:00] [ERR] [9] InternalCodeMigration: Migration "20250420070000_MigrateActivityLogDb" failed
Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 1: 'no such table: ActivityLog'.
at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
at Microsoft.Data.Sqlite.SqliteCommand.PrepareAndEnumerateStatements()+MoveNext()
at Microsoft.Data.Sqlite.SqliteCommand.GetStatements()+MoveNext()
at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReader(CommandBehavior behavior)
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReader()
at Emby.Server.Implementations.Data.SqliteExtensions.Query(SqliteConnection sqliteConnection, String commandText)+MoveNext()
at Jellyfin.Server.Migrations.Routines.MigrateActivityLogDb.Perform()
at Jellyfin.Server.Migrations.Stages.CodeMigration.Perform(IServiceProvider serviceProvider, IStartupLogger logger, CancellationToken cancellationToken)
at Jellyfin.Server.Migrations.JellyfinMigrationService.InternalCodeMigration.PerformAsync(IStartupLogger logger)
at Jellyfin.Server.Migrations.JellyfinMigrationService.MigrateStepAsync(JellyfinMigrationStageTypes stage, IServiceProvider serviceProvider)