The gemara (Sanhedrin 6b) quotes R' Meir as being very harshly critical of Yehudah:
רבי מאיר אומר לא נאמר בוצע אלא כנגד יהודה שנאמר ויאמר יהודה אל אחיו מה בצע כי נהרוג את אחינו וכל המברך את יהודה הרי זה מנאץ ועל זה נאמר ובוצע ברך נאץ ה
Anyone who praises Yehudah for advocating that Yosef be sold instead of killed is insulting G-d, as how can you praise someone who encouraged selling his brother into slavery?
Tos on the spot asks how R' Meir could criticize Yehudah when Yaakov Avinu on his death bed praised Yehudah: גּ֤וּר אַרְיֵה֙ יְהוּדָ֔ה מִטֶּ֖רֶף בְּנִ֣י עָלִ֑יתָ (49:9! Tosfos answers that Yaakov was not praising Yehudah for sparing Yosef's life, but rather was praising Yehudah for confessing his guilt and not allowing Tamar to be killed. In other words, the way to read that pasuk is not מִטֶּ֖רֶף בְּנִ֣י, comma, עָלִ֑יתָ, but rather מִטֶּ֖רֶף comma, i.e. from the killing of innocent Tamar, בְּנִ֣י עָלִ֑יתָ you my son, Yehudah, rose up and did not do wrong. (see Maharasha as well)
Yet if we look at the Yalkut Shimoni on that pasuk, the Yalkut writes:
אָמַר לֵיהּ יְהוּדָה בְּנִי, מְסֻלָּק אַתָּה מֵאוֹתוֹ עָוֹן שֶׁאָמַרְתָּ ״טָרֹף טֹרַף יוֹסֵף״
And Rashi in his first pshat on the pasuk echoes the same:
מטרף – ממה שחשדתיך בטרף טורף יוסף חיה רעה אכלתהו (בראשית ל״ז:ל״ג), וזה יהודה שנמשל כארי
So hadra kushya l'duchta: how can R' Meir accuse Yehudah of wrongdoing when Yaakov proclaims his innocence?
R' Yehudah Deri in his sichos on the parsha answers that both R' Meir's perspective and Yaakov Avinu's perspective are true. The brothers were on the verge of literally killing Yosef. If Yehudah had not stepped in, that would have been the end. מִטֶּ֖רֶף בְּנִ֣י עָלִ֑יתָ -- Yehudah saved Yosef's life.
Yet, at the same time, as Rashi writes on the sugya in Sanhedrin, כנגד יהודה. שהיה לו לומר נחזירנו לאבינו אחרי שהיו דבריו נשמעין לאחיו, once Yehudah had his brothers' ears, he could have done so much more than simply prevents Yosef's murder. He could have brought his brother home.
Yaakov Avinu looked at the b'poel of Yehudah's actions, that without him Yosef was finished. R' Meir looked at the b'koach of Yehudah, the potential that he wasted in not doing more.
I think these two perspectives are built into Yehudah's makeup. The Torah tells us that Leah gave her child the name Yehudah because "ha'pa'am odeh es Hashem," she wanted to praise Hashem. Immediately afterwards the Torah tells us "va'taamod mi'ledes," she stopped having children. Why after giving praise to Hashem was Leah suddenly not able to have more children?
Maor vaShemesh quotes the Chozeh miLublin:
והנה שמעתי מאדמ"ו הרב הקדוש מו' יעקב יצחק מלובלין הכ"מ זלה"ה במעשה דחוני המעגל במס' תענית שהתפלל על הגשמים עד שירדו גשמים מרובי' ולא היו צריכים להם עוד ובקשו ממנו שיתפלל עליהם שלא ירדו עוד אמר להם שיביאו לו פר הודאה יעוין שם והביאו לו והקריב ופסקו הגשמי' אמר אדמ"ו זלה"ה שהכוונה הי' כנ"ל כי אחר שהקריב פר הודאה בזה רימז שכבר יצאו מן הצער לגמרי ואינם צריכים עוד להטובה וממילא יפסקו הגשמי' וזה מרומז בפסוק שלפנינו אחר שאמרה לאה הפעם אודה את ה' וקראה שמו יהודה לשון הודאה ממילא הראה בעצמה שכבר קבלה כל הטובה בבנים ואינה צריכה עוד לטובה זו על כן ותעמוד מלדת
Imagine you sit down to a big banquet and the waiters start to bring out course after course of delicious food. You don't get up in the middle, put down your fork and knife, fold your napkin nicely, and go thank your hosts for such a nice evening. That's what you do at the end of the meal, not in the middle. If you do it in the middle your hosts will think you are leaving and don't care to stick around for the lavish desert that is coming along with the after dinner drinks.
"Ha'pa'am odeh es Hashem" is saying thanks in the middle of the meal. It signals that you are done and are going to take a pass on what is yet to come. B'poel, you are doing the right thing by thanking your host, but b'koach, you missed out on even more and better things.
Which of these differing perspectives to give greater weight to is the machlokes Shamai and Hillel as to how to light the menorah. Hillel held to add a candle each night, as each night b'poel the miracle was greater as the menorah continued to burn without additional oil. Shamai held to start with eight candles and subtract one on each night, as on each night the b'koach potential of what was to come grew less and less.