The problem was that in the feast of charity, which was an actual communal meal, some members of the body were being treated like lepers:
"When ye come together therefore into one place, this is not to eat the Lord's supper. {21} For in eating every one taketh before other his own supper: and one is hungry, and another is drunken. " (1 Corinthians 11:20-21)
Paul's criticism of them is that they are really not commemorating the Lord's unselfish sacrifice of Himself due to the selfish manner in which they are practicing it.
He then states the instructions given in instituting the supper, and that "as often as ye eat this bread, and drink this cup, ye do shew [manifest] the Lord's death till he come." {26}
Christians manifest His death for them by death to self in serving God and therefor others. Thus they were not manifesting recognition of Jesus death for them because they were not caring for the life of others. And because as often as ye eat this bread, and drink this cup, ye do shew [manifest] the Lord's death till he come," therefore the next verse says,
"Wherefore whosoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of the body and blood of the Lord. {28} But let a man examine himself, and so let him eat of that bread, and drink of that cup. {29} For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord's body. " (1 Corinthians 11:27-29)
Examining primarily concerns how you were treating each others, which recalls Jesus words about being reconciled before offering sacrifice, (Mt. 5:23,24) But there is nothing in here about the composition of the physical bread they ate, but not discerning or judging the "Lord's body" refers to either effectively denying what His death represents by their selfishness, as per v. 20 - "this is not to eat the Lord's supper" - or by failing to recognize the other members as part of the body and to them justice according.
Paul next reveals that this miscelebration was the reason that they were being chastened and judged, including death, which capital punishment for lack of care is consistent with O.T. penalty about not caring for the poor. (Ex. 22:22-24)
In further confirmation that this was the issue, Paul provides the remedy needed to avoid chastening, which was not by recognizing that the bread was really Jesus flesh, but by rightly judging what the sacrifice of Christ which they commemorated represented and acting accordingly; "Wherefore, my brethren, when ye come together to eat, tarry one for another. And if any man hunger, let him eat at home; that ye come not together unto condemnation. And the rest will I set in order when I come. " (1 Corinthians 11:33,34) "
This corresponds to what Paul said in the previous chapter, that "For we being many are one bread, and one body: for we are all partakers of that one bread. " (1 Corinthians 10:17) For the body of Christ to be in communion with Jesus broken body and shed blood in His death is to be communally consistent with Him who died for us and purchased us with His blood.
"For the love of Christ constraineth us; because we thus judge, that if one died for all, then were all dead: {15} And that he died for all, that they which live should not henceforth live unto themselves, but unto him which died for them, and rose again. " (2 Corinthians 5:14-15)
In the next chapter Paul further elaborates on the interdependence of the body, For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ." "That there should be no schism in the body; but that the members should have the same care one for another." (1Cor. 12:12,25)
And how superficial we are in this today. go.