It seems like the update for training may have inadvertantly changed something on how many skills horses were getting. I'm on my 4th horse since the patch and my average skill count at max level has gone down noticeably since.

1. It's rng.

2. What tier of the horse are we talking about? From my observations higher tiers have a lower chance of acquiring skills. It all depends on whether we train a horse from lvl 1 or, for example, a captured horse that has, for example, 8 or 10 lvl.

No we have only t6 and t7 and here it is much worse with skills than with t1-t5.

It also depends on what skills you can still learn.
Certain skills have a higher chance to be learned than other skills. For example, Fore-Chop, Hind-Kick and Quick-Back are 3 skills that have a high chance to be learned with some of the T8 horses.
So if those skills are still unlearned, you have a slightly higher chance to learn a new skill than if you had the same amount of skills but already have those 3 learned.

At the end of the day, it's all RNG and sometimes horses are just potatoheads and refuse to learn any skills.
Surely next horse will be much better. :D

... it seems horses are definitely getting fewer skills now

Yep, can confirm. Many in my guild have stated the same thing as with seasoned horse trainers (people who do it all the time). They secretly nerfed it sadly.

This is simply not true!