There are many instances that Baha'u'llah explicitly claims he is God

Baha'is will tell you that Baha'u'llah is not God, however there are many instances that Baha'u'llah explicitly claims he is God. These quotes are ignored by Baha'is and they usually act as if they don't exist. The concept of God in Baha'ism seems extremely contradictory at first but a careful study of Baha'u'llah's writings shows that he would change his claims depending on the audience: In his private tablets he openly claims to be God and yet in others he acts as if he is a normal person like all others. On the other hand Baha'i scripture and law clearly shows that Baha'u'llah considered himself God. I will show you a few examples:

• In his poem called the ODE of the Dove Baha'u'llah explicitly claims that he is the creator of Gods: " 110. My raining Cause made deities divine; all Lords have by My ample order thrived" Another translation states: "All Gods became Gods from the flow of my affairs and all Lords became Lords by the overflowing of my decree"
• You can find a bunch of quotes where Baha'u'llah makes explicit claims of being God here and here for example:

1. 'he who speaks in the most great prison (i.e. Acre) is the Creator of all things and the one who brought all names into being' (letter in Bahá' Allah Athar-i qalam-i a'la vol. 2 [Tehran, n.d., being a repaginated reprint of a collection of writings originally preceded by the Kitab al-aqdas, first printed Bombay, 1314/1896], p. 177);
2. 'verily, I am God' (letter in Ishraq Khavari Ma'ida, vol. 7, p. 208);
3. 'the essence of the pre-existent (dhat al-qidam) has appeared' (letter to Haji Muhammad lbrahim Khalil Qazvini in ibid, vol. 8, p. 113);
4. 'he has been born who begets not nor is begotten' ('Lawh-i milad-i ism-i a'zam' in ibid, vol. 4, p. 344, referring to Qur'an sura 112);

'the educator of all beings and their creator has appeared in the garment of humanity, but you were not pleased with that until he was imprisoned in this prison' ('Surat al-hajj' in Bahá' Allah Athar-i qalam-i a'la, vol. 4 [Tehran, 133 badi' /1976-77], p. 203).

• The Baha'i prayers: These are compulsory prayers that must be recited while Baha'is face Baha'u'llah or his grave. All kinds of thorny issues arise here. The first: when Baha'u'llah was alive and moving around you had no idea which direction to face. The second issue: how did Baha'u'llah recite these prayers? Which direction did he face? There is not a single documented instance of anyone ever seeing Baha'u'llah recite the Baha'i prayers. Why should he when he considers himself God.
• The Baha'i pilgrimage: Copied from the Muslim annual hajj pilgrimage. Muslims flock every year to the House of GOD, and Baha'is must flock to the House of Baha'u'llah in Baghadad (which was razed to the ground and doesn't exist) So why substitute God's house with Baha'u'llah's house for pilgrimage if you don't consider yourself anything but God?
• In previous religions God is considered the revealer of books but in Baha'ism, Baha'u'llah is considered the revealer of books. Again, an act that was solely reserved for God is now reserved for Baha'u'llah.

Openly stating that Baha'u'llah is God is taboo in Baha'ism and they try to hide this matter with great care. In fact, as you have observed even some of the ex-Baha'is here don't know about this matter. I wouldn't expect Baha'u'llah to make a claim less than God for Baha'ism is based on Babism and its founder the Bab who too considered himself and his successor (Azal) to be God. The Bab openly stated this in his will:
“Name of Azal, testify that there is no God but I, the dearest beloved. Then testify that there is no God but you, the victorious and permanent.” (The Bab's will)