Decreasing speed with an increasing number of GPUs

[whitemerc]

Here is cl:
hashcat -m 23800 -a 3 -o cracked_hash.txt hash.txt n?1?1?1?1?1?1?1?1 --increment --increment-min=8 --increment-max=12 -1 abcdefghijklmnop -O -S -d 1,2,3,4,5

only 1 GPU 3070
Speed.#1.........:    21415 H/s (25.48ms) @ Accel:1 Loops:16384 Thr:512 Vec:1

2 GPUs (3070 + 3060Ti)
Speed.#1.........:    15372 H/s (25.38ms) @ Accel:2 Loops:16384 Thr:256 Vec:1
Speed.#2.........:    13892 H/s (20.69ms) @ Accel:1 Loops:16384 Thr:512 Vec:1
Speed.#*.........:    29265 H/s

5 GPUs (2 3070 + 3 3060Ti)
Speed.#1.........:    5805 H/s (25.45ms) @ Accel:1 Loops:16384 Thr:512 Vec:1
Speed.#2.........:    5556 H/s (21.10ms) @ Accel:1 Loops:16384 Thr:512 Vec:1
Speed.#3.........:    5854 H/s (21.14ms) @ Accel:1 Loops:16384 Thr:512 Vec:1
Speed.#4.........:    5895 H/s (25.24ms) @ Accel:1 Loops:16384 Thr:512 Vec:1
Speed.#5.........:    5542 H/s (21.48ms) @ Accel:1 Loops:16384 Thr:512 Vec:1
Speed.#*.........:    28652 H/s

So 5 GPUs are slowly than 2 GPUs

core i7 6700, 48G RAM, ssd.
CUDA.Version.: 12.2
ubuntu 22.04
hashcat 6.2.6

Any suggestion how to fix this?