What is your advice to someone who finds hypocrisy (riya') creeping into their recitation of the Quran and their prayers, and how can one magnify sins and belittle good deeds to avoid conceit and arrogance?

Fear of riya' (showing off) is commendable. A Muslim should strive for sincerity and purify their intention solely for Allah the Almighty. They should frequently seek refuge in Allah from shirk (polytheism) by saying: "O Allah, we seek refuge in You from knowingly associating anything with You, and we seek Your forgiveness for what we do not know." One must be careful not to let Satan discourage them from good deeds under the pretext of fearing riya'. Indeed, abandoning a good deed for the sake of people is riya', and performing it for their sake is shirk.

As for ‘ujb (self-admiration), it dissipates by realizing that all blessings are from Allah's grace and enabling, and by fearing their removal if one were left to their own devices.

Regarding a servant's deeming their sins great and belittling the good they have offered, this is a beautiful character with Allah. It means that the servant knows that everything they do warrants an excuse, and everything that comes from truth warrants gratitude, and that they see no limit to their loyalty. The servant apologizes for their shortcomings in their actions, even the good ones, and fears that they may not be accepted. This stems from witnessing one's own deficiency and true love. The second principle is to magnify everything that comes from Allah and to acknowledge that it necessitates gratitude, and the inability to thank Him sufficiently.