ETC mining and 3GB boards

Hi community

Since May22nd, 18:30, all my videocards hosting 3GB VRAM suddenly felt in hashrate from 30 to 50%

To me 3GB Epoch is not yet reached (around June 15th), and got no alert with lolminer 1.50
DAG is still corretly created

GPU3 was previously mining @ 28.7 MH/s,not 22/23

Am I the only one to see that ?