What changed between Shemos and Bamidbar regarding the Jews complaining?

Question

In Shemos 16:2, Bnai Yisrael complain to Moshe and Aharon:

וַיִּלּוֹנוּ כָּל עֲדַת בְּנֵי יִשְׂרָאֵל עַל משֶׁה וְעַל אַהֲרֹן בַּמִּדְבָּר:‏

Hashem listens to their complaint for meat, and grants it to them.

But later in Bamidbar Perek 11:1-4, the Jews complain and Hashem gets angry and sends fire towards them. Why the dramatic change in Hashem's response to the complaining of the Jews?

MY question seeks two answers. One, a distinction between the two episodes and two, perhaps a thematic answer comparing the nature of the Jews in Shemos vs Bamidbar.

Answer 1

Shmos 16:2 was the initial complaint when they left Egypt because they had not yet learned to fully trust in Hashem. He sent the manna and gave them the chance to learn how to follow his orders. Note that He gave them the chance to not leave any over and to refrain from gathering on Shabbat. 17:2 contains the complaint about water and the miracle of striking the rock. It is followed them by the punishment of Amalek attacking.

Bamidbar is 40 years later and they should have learned the lesson of Hashem having given them the manna and the water for the entire trek in the dessert. Rav Hirsch points out the it begins with them acting as if they were in mourning for their own death. They in effect talked themselves into rebelling and complaining. Additionally, they did not actually have anything that they could justify complaining. Hashem caused the fire to break out at the end of the camp and they cried to Moshe (before anyone was killed) and Moshe prayed for them and the fire (caused by them) died down. Rav Hirsch says that they were bad in the Ears of Hashem since they deliberately set themselves against Hashem and deliberately complained.

After this they talked themselves into complaining about the manna and pretending that it was too bland and boring.

Rav Hirsch states that they let the Eirev Rav act as a poison in their midst and pull them down. Instead of being a minority in the world that would raise the other nations, they allowed the minority in them to pull them down.

Answer 2

Numbers 11:21:

וַיֹּאמֶר֮ מֹשֶׁה֒ שֵׁשׁ־מֵא֥וֹת אֶ֙לֶף֙ רַגְלִ֔י הָעָ֕ם אֲשֶׁ֥ר אָנֹכִ֖י בְּקִרְבּ֑וֹ וְאַתָּ֣ה אָמַ֗רְתָּ בָּשָׂר֙ אֶתֵּ֣ן לָהֶ֔ם וְאָכְל֖וּ חֹ֥דֶשׁ יָמִֽים׃

And Moses said: ‘The people, among whom I am, are six hundred thousand men on foot; and yet Thou hast said: I will give them flesh, that they may eat a whole month!

You can understand the difference clearly via Sifrei Bamidbar 95:1. I am excerpting some parts from Sefaria.org's English translation:

R. Shimon b. Yochai said: R. Akiva expounded this in one way, and I, in two ways, and my words seem more cogent. R. Akiva expounds it plainly, viz. (Ibid. 22) "If flocks and herds are slaughtered for them will it be sufficient for them?" Even if you give them all the flocks and herds (in the world), will it be sufficient for them? And I understand it as follows: "If flocks and herds are slaughtered for them will it be sufficient for them?" Even if you give them all the flocks and herds in the world, they would grumble. For is it because they have no meat that they are grumbling? Is it not written of the exodus from Egypt (Shemot 12:38) "And also a great mixture (of proselytes) went up with them, and flocks and herds, etc."? I might think they ate them in the desert. It is, therefore, written (Bamidbar 32:1) "And the sons of Reuven and the sons of Gad had much cattle, etc." It is only that they were looking for a pretext to abandon the L-rd. (Ibid. 11:22) "If all the fish of the sea are gathered for them"? Even if you gave them all the fish in the sea they would grumble. For is it because they have no fish that they are grumbling? Did not the well of Miriam accompany them in the desert and supply them with more than their fill of fish? It is only that they were looking for a pretext to abandon the L-rd.

In short, in the 1st occurrence, in Exodus, they didn't have food because the dough (matzah) ran out. So asking for bread was legit. Asking for meat wasn't as legit. because, technically, man does not need meat to survive. But G-d accommodated them, at that time.

In the 2nd situation, it was clear that they had sufficient food and fish, among other items. There was no reason to complain.