Don't know how the adresses are with bypass mode.
But in normal mode 192.168.100.1 is for the Starlink dishy. 192.168.1.1 is for the Starlink router.
If you connect the MT to the Starlink router in normal mode , it's connected to the 192.168.1.0/24 network. Then you get an address like 192.168.1.1xx from the Starlink router on the MT router.
A route for 192.168.100.1/24 with 192.168.1.1 as gateway is then needed.
Bypass might give your an address in the 192.168.100.0/24 range (so then that route is not needed)
Using NAT in the MT
For your LAN network adressing that is mostly different , "masquerade" or SRC-NAT can be used on the eth1 interface of the MT, to the Starlink router.
For the default config of a MT in Home gateway (Home AP etc) , adding eth1 to the "WAN interface list" will do the trick. Eth1 is then an internet WAN connection, and has a DHCP client.
The masquerade NAT rule for the WAN interface list members should be there already by default.
Eth1 is not added as port on the LAN bridge. LAN Bridge that usually caries it's own LAN subnet and DHCP server (your 192.168.0.0/24)
The Starlink then only sees the Eth1 address of the MT as connected.
Not using NAT in the MT
If you don't want the NAT used in masquerade on the MT, then all devices must be in the address range of the Starlink LAN. (192.168.100.0) or in a
extra subnet set as LAN in the Starlink router .
(If this can be done. I have no access to this setting in my Starlink router).
ETH1 can then be a port on the bridge, which carries the DHCP client. There is no routing or NAT in the MT in this bridged case.
So I don't understand what you want with
I tried adding a static route destination address of 192.168.100.1 to the gateway of my router 192.168.0.1 and its subnet is 255.255.255.0
Client devices should use the MT router as default gateway (192.168.0.1?) , or 192.168.100.1/32 should be properly routed to this MT via other gateways.