Sforno on Numbers 11:4/ספורנו על במדבר י״א:ד׳

1וישובו ויבכו, they again pretended to have justified complaints, testing G’d’s patience. This time they cried that they had agreed to leave Egypt. This was equivalent to insulting the Presence of the Shechinah that had honoured them with its presence amongst them. Moses tells them this explicitly in verse 20 when he said: יען מאסתם את ה' אשר ,בקרבכם ותבכו לפניו לאמור למה זה יצאנו ממצרים?, “because you despised the Lord Who is in your midst and you cried, saying: “why is this that we left Egypt?”

2מי יאכלנו בשר?, They said this in order to test if He would permit incestuous relations to His people (compare Psalms 78,18 where Assaph says וינסו א-ל בלבבם לשאל אוכל לנפשם, they asked openly for meat, and in their hearts for sexual gratification other than by their wives).