Roll on the bigger Champions League games when it will be full and the atmosphere raucous.
The atmosphere against Liverpool in 2018 and Spurs in 2019 was superb. Likewise it would have been off the scale in 2020 for Real Madrid if not for Covid. Same last season for Dortmund and PSG.
Liverpool's famed "magical European nights under the lights" (puke) was built on the historic norm on having lower attendances in the earlier rounds or group stage matches. The attendances below were for the first 5 seasons when they went on to actually win the European Cup. I've highlighted the low and the high.
1976/1977
R32: 22,242
R16: 42,275
QF: 55,043
SF: 50,611
1977/1978
R16: 39,835
QF: 48,364
SF: 51,500
1980/81
R32: 21,013
R16: 36,182
QF: 37,255
SF: 44,543
1983/1984
R32: 14,985
R16: 33,063
QF: 39,096
SF: 36,941
2004/2005
LG: 33,517
R16: 40,952
QF: 41,216
SF: 42,259