I agree with the last speaker. Man cannot bless God. The main reason is that Hebrews 7:7 states categorically that without any exception or any doubt. It is always the lesser who is blessed by the greater. Find below 3 different versions of this text:
a) Without all (or any) contradiction, the less is blessed by the better. [KJV]
b) Without a doubt the inferior is blessed by the superior (CSB)
c) It is beyond any dispute that the inferior is blessed by the superior. (ESV)

Given all the above and similar versions of Hebrews7:7, it must be obvious that no human being can bless God since God is by definition superior to everyone, and everyone is inferior to God. The emphasis placed on this statement is intended for us to consider it as a fundamental principle comparable to an axiom in mathematics or logic. The author of Hebrews applies this principle in arguing that because the Patriarch Abracham paid a tithe or 10% tribute to Melchizedek (a priest of the Most High), who is a representation of the Lord Jesus Christ, Christ is superior to Abraham, and Christ's covenant is equally superior to Abraham's covenant. Hebrews 7: 1-6.

The claim that man can bless God is therefore not only a violation of this fundamental principle, but a logical contradiction in terms, and the height of human arrogance; if not claimed out of ignorance or a mistake, but intentionally.

But if so, why do we find so many references to man blessing God in the Old Testament, especially in the Psalms such as Psalm 103:1-3? "Bless the Lord oh my soul, and all that is within me. Bless his holy name. Bless the Lord oh my soul, and forget not his benefits." There are at least 36 of such references to man blessing God in the Psalms and other parts of the O.T.
Error Theory:
They are however based on a wrong translation and therefore not intended to violate the fundamental Principle in Hebrew 7:7 or to claim superiority to God. Historically, most of the English versions of the Bible we use were translated from the Septuagint (or Greek version of the original Hebrew text called Masoretic text). In the Septuagint the Greek word for bless is euangelou, which literally means "I speak well of." So, the translation should be "bless" when God is speaking well of man, and "praise," when man is speaking well of God as in honoring him for his grace and mercy. This sort of context-dependent translation should be preferred over the literal translation which is responsible for the misleading translation. Fortunately, most of the new translations such as NIV, ESV, Good News, Living Bible etc. have already replaced bless with praise or honor in Psalm 103 and similar passages throughout the Bible.

Thanks for your attention. God bless you for your humility!