Doesn't the first class feast trump the obligation to fast and abstain since it is like a Sunday?

Rorate Caeli says the same, fast and abstinence.

https://rorate-caeli.blogspot.com/2012/05/ember-days-during-pentecost.html

Doesn't the first class feast Tɾυmρ the obligation to fast and abstain since it is like a Sunday?

Not all first class feasts are equal, penance wise. Only the holy days of obligation are treated as Sundays.  The annunciation, always during Lent, is still a fast day.  

If you are a consistently traditional Catholic, the ember days this week are fast days (and partial abstinence) which bind under pain of mortal sin.  This is true whether or not you accept the 1950s liturgical reforms authored by Bugnini, and is reflected in the calendars of both SGG, SSPV, and CMRI.

If you believe Bergoglio is the Pope, then the only fast days which bind are Ash Wednesday and Good Friday.  Fasting laws are disciplinary in nature, and changes of them constitute a material alteration, which is perfectly legal for a true Pope to enact.
If you are emotionally attached to fasting in the old way despite acknowledging the arch-modernist bergoglio as the Vicar of Christ, then please: fast according to the traditional norms and research pre-Vatican 2 ecclesiology; which will expose these degenerate destroyers as false popes, and justify you in utterly rejecting their false laws.