Some skills used in battle do reduce concentration but these have done so since they were added (years ago) so it doesn't apply to any "recent changes".
This thread got me to look through the code in detail and I found no recent changes that affect concentration. The most recent ones were some time ago and they actually made concentration better in certain scenarios.
Note that complains about lost conc getting worse really isn't a new debate though, it comes around every couple years.
It does seem that the random number generator is a bit on the "streaky" side though. I've seen this by just watching players random for items. You might get a 98 and a 99 right next to each other.