>>8112473Obviously a few of the images are just straight-up photography, maybe with some post-processing.
Most of the rest would have been made possibly with Adobe Photoshop, or more likely with Adobe Illustrator, or even both of those programs, using a combination of random lines, shapes, fills, gradients, filter and layer effects, and plenty of (semi-)transparent layers.
While the remainder are either hand-drawn or are collages also made in Photoshop (other art programs are available) or they were generated using other programs, e.g. Apophysis for the various fractal flame images.
I dare say with some careful training/prompting you could probably get one of the AI art apps to start generating abstract art like some of these images.