Pop in C (with barre) — syncopated muted strums
As already established for F on this grid's simple muted version, the barre needs firm pressure rather than easing off to mute cleanly. Under the syncopation, that grip now has to hold in rhythm, with no dead time to stabilise before each hit.
Tips
If simple muting on F isn't reliable yet, work on it in isolation first before adding the syncopation.
Keep the barre finger firmly in place throughout the syncopated pattern, without trying to ease it.
On C, G and Am, the palm does all the work with no barre constraint: consciously contrast that with F.
Chord progression — C
Bar 1
C
I
Bar 2
G
V
Bar 3
Am
vi
Bar 4
F
IV