Is the fear of Allah's lack of success and forgiveness in this world and the hereafter justified, after angering one's mother and seeking her forgiveness, while harboring a negative view of her due to her irregular prayer and some of her manners? And what should be done to remove this negative view?

The greatest act of righteousness towards a mother is to strive for her guidance, especially concerning prayer, by advising her kindly or by having someone else advise her. Your dislike for your mother's bad behaviors or your annoyance with them is not an act of disobedience (ʿuqūq). However, the problem arises if any harm emanates from you or if you anger her through neglect. Your fear of the bad consequences of her anger is well-placed, and you have done well by seeking her forgiveness. You must strive to be righteous towards her and earn her pleasure.