Strange Behavior about VM NICs

[CEllenvia]

so hi there,
i have a proxmox ve version 7.2-11 with "Linux pve 5.15.30-2-pve #1 SMP PVE 5.15.30-3 (Fri, 22 Apr 2022 18:08:27 +0200) x86_64" kernel inside of a VMware ESXi environment. there's a DHCP service outside of this machine, and use 192.168.50.0/24. now i have installed vm in the proxmox, and it CAN get the IP address, but when i ping anything out of 192.168.50.0/24, strange thing happens: no apply. i checked the tcpdump and found that proxmox FORWARDED the package, but the vm's NIC seems to drop them. so any ideas on troubleshooting?
configs:
/etc/network/interfaces

root@pve:~# cat /etc/network/interfaces
# network interface settings; autogenerated
# Please do NOT modify this file directly, unless you know what
# you're doing.
#
# If you want to manage parts of the network configuration manually,
# please utilize the 'source' or 'source-directory' directives to do
# so.
# PVE will preserve these directives, but will NOT read its network
# configuration from sourced files, so do not attempt to move any of
# the PVE managed interfaces into external files!

auto lo
iface lo inet loopback

iface ens33 inet manual

auto ens36
iface ens36 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.50.35/24
        gateway 192.168.50.1
        bridge-ports ens33
        bridge-stp off
        bridge-fd 0

auto vmbr1
iface vmbr1 inet static
        address 192.168.47.0/24
        bridge-ports none
        bridge-stp off
        bridge-fd 0

iface vmbr1 inet6 static
        address fe80:1877::/32

qm config

root@pve:~# qm config 103
bios: ovmf
boot: order=scsi0;ide2;net0
cores: 2
efidisk0: storage_2:103/vm-103-disk-0.qcow2,efitype=4m,pre-enrolled-keys=1,size=528K
ide2: local:iso/ubuntu-22.04.1-live-server-amd64.iso,media=cdrom,size=1440306K
machine: q35
memory: 2048
meta: creation-qemu=7.0.0,ctime=1665752363
net0: rtl8139=62:CB:01:64:0B:AF,bridge=vmbr0
numa: 0
ostype: l26
scsi0: local-lvm:vm-103-disk-0,size=25G
scsihw: virtio-scsi-single
smbios1: uuid=fe07f1c6-6889-4d72-a7da-1c01d578ef65
sockets: 1
vmgenid: 776f59b6-2575-4c54-a270-e2e539ef644b

tcpdump on Proxmox

root@pve:~# tcpdump -i vmbr0 icmp
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on vmbr0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
08:40:15.381528 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 1, length 64
08:40:15.381548 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 1, length 64
08:40:15.389882 IP 39.155.141.16 > 192.168.50.172: ICMP echo reply, id 4, seq 1, length 64
08:40:16.383287 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 2, length 64
08:40:16.383327 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 2, length 64
08:40:16.391988 IP 39.155.141.16 > 192.168.50.172: ICMP echo reply, id 4, seq 2, length 64
08:40:17.407523 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 3, length 64
08:40:17.407562 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 3, length 64
08:40:17.416156 IP 39.155.141.16 > 192.168.50.172: ICMP echo reply, id 4, seq 3, length 64
08:40:18.431535 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 4, length 64
08:40:18.431572 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 4, length 64
08:40:18.440197 IP 39.155.141.16 > 192.168.50.172: ICMP echo reply, id 4, seq 4, length 64
08:40:19.455151 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 5, length 64
08:40:19.455193 IP 192.168.50.172 > 39.155.141.16: ICMP echo request, id 4, seq 5, length 64