Is it normal to be friends with someone and not like their art at all?

The quality of a work of art is a subjective judgement. In other words, you thinking that your friend's art is ugly is nothing more than your opinion. Maybe 99% of people would agree with you, but that's still just a whole bunch of opinions, and opinions often change over time. The classic example is Van Gogh: his art was widely ridiculed when he was alive and he only managed to sell two paintings and a few drawings, but he is now acknowledged as a great artist.

All you can really say for sure is that your friend's art doesn't speak to you. That doesn't prove your friend really is a crap artist and they're deluded to believe otherwise, and nor does it prove that you're incapable of appreciating good art when you see it. It simply means that, in this particular form of communication, you and your friend are not on the same wavelength.

Something else you might bear in mind is that artists develop over time. What your friend is producing now might not be technically competent or unappealing to you in some other way, but if they're seriously into art and keep at it, that may well change. For the last year or so, my twelve-year-old daughter has been going through a phase where she's into creating drawings of female animé-style characters. It's getting a bit boring for the two adults who are the only people to visit her bedroom gallery, but her technique and speed have improved a lot, and I'm sure she'll eventually get bored and move on, using the skills she's learned to produce other art that's more interesting.

Totally normal...

Friendship is about a lot of things - and it does not mean that you necessarily (or have to) like all their personal choices or activities.

It means that you share a certain core set of values and appreciation for the other person.

Pay attention to the good things, and ignore the distractions....

Honestly, I don't like any of my friends art either. It's fine to not like someone else's creations.

Yo, on da YouTube I follow this hoe called Banana Jamana. Her art ain't dat good, fam, but I like looking at da bitch's quirkiness and listening to her soft voice.
Her nose kinda weird though but she got a good vibe, nahmean?

You're your own person with your own discretion

I don't know what kind of person you are, but I would recommend being supportive. Art is self expression no matter the skill level, and if you're their friend I'm guessing you care about them?

Unless you two are informal/familiar with each other, then maybe you can joke about a particular aspect so it's more like constructive criticism

Most art is shit and the people who make it are usually pretentious pseudo intellectual assholes

Yes, you can like someone's personality without having the same tastes or liking their creations.

Just be tactful in how you express it

The art is separate to the person.

My friend is married to a professional folk singer. She's not into folk and never listens to his band's music, unless she happens to go to one of his gigs, and even then she is just there to be supportive and socialise, rather than listen to the music. I don't doubt that she loves her husband.

Do it with caution.