I checked the official UEFA website and many matches will be played on neutral venue indeed:
1st leg:
Leipzig - Liverpool in Hungary
Atl. Madrid - Chelsea in Romania
Mönchengladbach - Man. City in Hungary
2nd leg:
Everyone plays at their home venue.
I see this as an advantage loss for Leipzig, Atletico Madrid and Gladbach. Maybe we still don't have supporters in the matches yet but playing in your own stadium still is a plus. Maybe it won't affect Leipzig and Atletico Madrid much but Gladbach is in a worse situation now I think.

Manchester City could win that game easier than I expect. Of course the things I say will be dependent on the conditions of these stadiums too.