Need help with tap breakage

Hey guys, I need some advice with taps So we’ve been using spiral flute taps (TiN coating. Same as the picture) from YG-1 for tapping blind holes for a while now. But for some reason, for about 3 months the taps keep breaking very often. In particular M8x1.25 and M6x1.0 taps on deep blind holes On CNC lathes

1. The holes have been drilled per spec (for the M8 the hole is 6.8mm and for the M6 its 5.1mm)
2. We use a compensator for centering the tap
3. The hole has a chamfer for better tap entry
4. The coolant % on the machine is at 10%
5. The tool is on center
6. Speed is low (rpm is 200)
7. For the M8 tap the thread is required to be 25mm deep and the hole is drilled 31mm. For the M6 thread the depth of the hole is 30mm and the thread depth required is 20mm
8. The material is S355 steel (low carbon steel with a yield strength of 355 N/mm2)
9. Have tried peck tapping but still the same
10. The tool keeps breaking at the bottom of the hole.

Any help would be much appreciated