It might be due to the fact that ETL2 runs on snaps/sv_fps "40" and ETL1 on "20" value. Higher snaps value improves the hit registration (to make it simple, it's something like 64 vs 128 tick in CS:GO or Valorant). So the hitreg on ETL2 will be always better, not mentioning the higher load on ETL1 which makes players lose packets, etc. ETL1 can't run on snaps "40" because the load is too big (too many players).